Dear student,
Let x = the angle
Let y = x's complement
x + y = 90
x = 1/4y
on the second equation multiple both sides by 4 to get rid of the fraction
4x = y
now plug this value in for the variable y into the first equation
x + 4x = 90
5x = 90
divide both sides by 5 to get x by itself
x=18
answer: the measurement of the angle is 18
the complement is 72
I hope you understand the answer.
Your teacher.