If the price changes from $50 to $70, what is the percent change?

• A. 20% increase
• B. 40% increase
• C. 40% decrease
• D. 60% increase

Answer: (B)

Percent change compares how much something has changed relative to where it started. The price goes from 50 to 70, so the change is 70 − 50 = 20. Relative to the original price of 50, that change is 20/50 = 0.4, which is 40%. Since the price goes up, it’s a 40% increase. The other options don’t fit: a 20% increase would require only a $10 rise, a 40% decrease would mean the price fell to $30, and a 60% increase would require a $30 rise.