Which three go together? Why do they go together?

A double number line with 6 evenly spaced tick marks. On the top number line, starting with the first tick mark, zero, 5, 10, 15, 20 and 25 are labeled. On the bottom number line, starting with the first tick mark, zero percent, 25 percent, 50 percent, 75 percent, 100 percent and 125 percent are labeled.

For each problem, complete the double number line diagram to show the percentages that correspond to the original amount and to the new amount.

1. Last year, scientists counted 12 foxes in a conservation area. This year, they counted 50% more than that. How many foxes did they count this year?

   

   A double number line for “number of foxes” with 4 evenly spaced tick marks. On the top number line, zero is on the first tick mark and the remaining tick marks are not labeled. On the bottom number line starting with the first tick mark zero percent, 50 percent, 100 percent, and 150 percent are labeled.

2. After replacing some grass with rocks, a business decreased its water usage by 20%. If their old water usage was 15,000 gallons per week, how much do they use now?

   

   A double number line for “water usage in gallons” with 7 evenly spaced tick marks. On the top number line the number zero is on the first tick mark and the remaining tick marks are not labeled. The bottom number line, starting with the first tick mark, zero percent, 20 percent, 40 percent, 60 percent, 80 percent, 100 percent, and 120 percent are labeled.

3. A school had 1,200 students last year and only 1,080 students this year. What was the percent decrease in the number of students?

   

   Double number line, top line number of people, evenly spaced tick marks labeled 0, 120, 240, 360, 480, 600, 720, 840, 960, 1080, 1200. Bottom line, corresponding tick marks, first labeled 0% and the rest blank.

4. One week, gas was \$1.25 per gallon. The next week, gas was \$1.50 per gallon. By what percentage did the price increase?

   

   A double number line for “price of gas in dollars” with 9 evenly spaced tick marks. On the top number line starting with the first tick mark zero, zero point 2 5, zero point 5, zero point 7 5, one, one point 2 5, one point 5, one point 7 5 and 2 are labeled. On the bottom number line, zero percent is on the first tick mark and the remaining tick marks are not labeled.

5. After a 25% discount, the price of a T-shirt was \$12. What was the price before the discount?

   

   A double number line for “price of shirts in dollars” with 6 evenly spaced tick marks. On the top number line, the number zero is on the first tick mark and the remaining tick marks are not labeled. On the bottom number line, starting with the first tick mark, zero percent, 25 percent, 50 percent, 75 percent, 100 percent and 125 percent are labeled.

6. Compared to last year, the population of Boom Town has increased 25%. The population is now 6,600. What was the population last year?

   

   A double number line for "number of people" with 6 evenly spaced tick marks. For the top number line, the number 0 is on the first tick mark and the remaining tick marks are blank. For the bottom number line, starting with the first tick mark, the percentages 0%, 25%, 50%, 75%, 100%, and 125% are labeled.

Green sea turtles live most of their lives in the ocean, but they come ashore to lay their eggs. Some beaches where turtles often come ashore have been made into protected sanctuaries so that the eggs will not be disturbed.

1. One sanctuary had 180 green sea turtles come ashore to lay eggs last year. This year, the number of turtles increased by 10%. How many turtles came ashore to lay eggs in the sanctuary this year?

2. At another sanctuary, the number of nesting turtles decreased by 10% between last year and this year. This year there were 234 nesting turtles. How many nesting turtles were at this sanctuary last year?