A price increases from 80 to 100. What is the percent change?

• A. 25%
• B. 20%
• C. 12.5%
• D. 33%

Answer: (A)

Percent change is the increase or decrease relative to the original value. It’s calculated as (new minus old) divided by old, times 100. Here, the price goes from 80 to 100, so the increase is 20. 20 divided by 80 equals 0.25, which is 25%. So the price has increased by 25%. You can also see this by noting that 100 is 1.25 times 80, meaning a 25% rise. The other options don’t fit: a 20% increase would give 96, 12.5% would give 90, and 33% would give about 106.4.