let
x-------> the greater angle
y-------> the smaller angle
we know that
x+y=90------> equation 1
y=x/5-------> equation 2
substitute equation 2 in equation 1
x+[x/5]=90-----> multiply by 5 both sides------> 5x+x=450
6x=450
x=75
y=x/5-----> y=75/5-----> y=15
the answer Part a) is
the greater angle is 75°
the answer part b) is
the smaller angle is 15°