Question 573550
One of the equations is stated in the question:
a=4b
For the other equation you have to know that the sum of the angles in a triangle add up to 180
Since one is 90, we get:
a+b+90=180
subtract 90 from both sides to get:
a+b=90
now we can sub in 4b for a
4b+b=90
combine like terms
5b=90
divide both sides by 5
b=18
Sub in 18 for b in either of the two equation
a=72