Question

The sum of two complementary angles is 90°. For one pair of complementary angles, the measure of the first angle is 15 less than twice the measure of the second angle. Write a system of equations that can be used to determine the measure of the first angle, a, and the measure of the second angle, b.

Answer 1

a + b = 90
a = 2b - 15

2b - 15 + b = 90
3b - 15 = 90
3b = 90 + 15
3b = 105
b = 105/3
b = 35 <== second angle

a = 2b - 15
a = 2(35) - 15
a = 70 - 15
a = 55 <== first angle

Answer 2

Answer: The measure of angle a is 90-25=65° and the measure of angle be is 25°.

Explanation:

Let the two complementary angles be 'a' and 'b'.

So, the sum of two complementary angles is 90°.

So, it becomes,

`a+b=90^\circ---------------(1)`

First angle is 15 less than twice the measure of the second angle.

So, it becomes,

`a=2b-15-------------(2)`

Put the equation (2) in equation (1), we get

`a+b=90^\circ\\\\2b-15+b=90^\circ\\\\3b+15=90^\circ\\\\b=90-15\\\\3b=75^\circ\\\\b=(75)/(3)\\\\b=25^\circ`

Hence, the measure of angle a is 90-25=65° and the measure of angle be is 25°