Help me with this question please

Question

In a survey, a group of students were asked to name their favorite elective class. There were 15 students who chose “other."

How many students participated?

art-30%

physical education-60%

Answer 1

150 students participated. 30 percent and 60 percent, equal 90 percent. With a whole 15 students equaling the remaining 10 percent. So, these percentages are to be multiplied by 15.

15 * .10 = 1.50

15 * .30 = 4.50

15 * .60 = 9.00

1.50 +4.50 +9.00 = 150