Word problem help

Question

the ratio of the measures of two angles of a triangle are 1:5. if 9 degrees is added to the smaller and 15 degrees is added to the larger, their ratio is 1:4. what is the measure of the smaller angle?

Answer 1

1:5

1x/5x

(1x+9)/(5x+15)=1/4

cross multiply

4(x+9)=1(5x+15)

4x+36=5x+15

36-15=5x-4x

21=x

1x=21

5x=105

21º is the smaller angle

105º is the larger angle

(21+9)/(105+15)=30/120=3/12=1/4