i don’t know how to find the answer

Question

At last month's trivia competition, 20 questions were about history and geography, and the other 35 questions were about pop culture. This month, the number of history and geography questions increased by 15%, while the number of pop culture decreased by 20%.

Find the percent change in total number of questions from last month to this month.

Answer 1

20 history and geography questions last month is increased by 15%. 

20 x .15 = 3

20 + 3 = 23

 

35 pop culture questions last month is decreased by 20%.

35 x .20 = 7

35 - 7 = 28

 

Total questions last month: 35 + 20 = 55

Total questions this month: 28 + 23 = 51

Difference in the number of questions: 55 - 51 = 4

4 is what % of 55? 

 

55X=4

55X/55=4/55

X=.07

.07 X 100 = 7%

 

There was a 7% decrease in the total number of questions from last month to this month.