A stock price rose from 40 to 52. What was the percent increase?

Percent increase is the change divided by the original value: $\frac{52-40}{40}=\frac{12}{40}=0.30$, or $30\%$, choice H. Choice F ($12\%$) reports the change in dollars as a percent. Choice G ($23\%$) divides the change by the new value, $\frac{12}{52}$, but a percent increase is measured against the original. Choice J ($130\%$) is the new price as a percent of the old price, $\frac{52}{40}$, and does not subtract the original $100\%$. Check: $30\%$ of $40 is $12, and $40+12=52$.