Explanation

50 as a percent of 30 is \(\frac{50}{30} \times 100\)% = 166.6%.

(Note: it’s incorrect to calculate “50 percent of 30,” which is 15. This asked for 50 as a percent of 30, which is equivalent to asking, “What percent of 30 is 50?”)

To find the percent increase from 30 to 80, use the percent change formula:
Percent Change = \(\frac{Difference}{original} \times 100\)%
Percent Change = \(\frac{80-30}{30} \times 100\)% = 166.6%

The two quantities are equal. Note that doing the final calculation in each quantity is not necessary, because both equal \(\frac{50}{30}\times 100\).