Question

Please help needed!!! Help me!!!

Answer 1

a = 85°

Step-by-step explanation:

Method 1

5x = 2x + 57° (An exterior angle of a triangle is equal to the sum of its two interior opposite angles)

3x = 57°

x = 57/3 = 19°

a = 180 - 57 - 2x

a = 180 - 57 -2(19)

a = 85°

Method 2

2x + a + 57° = 180°

2x + a = 123° ==> 1

5x + a = 180°

x = (180° - a)/5 ==> 2

By substitution

2((180° - a)/5) + a = 123°

(360° - 2a)/5 + a = 123°

(360° - 2a)/5 = 123° - a

360° - 2a = 5(123° - a)

360° - 2a = 615° - 5a

-2a + 5a = 615° - 360°

3a = 255°

a = 85°