Answer:

x=10

m<a = 10°

m<b = 90°

m<c = 80°

Step-by-step explanation:

The sum of Complementary angles is 90°

So, the sum of <a and <c is equal to 90.

Equation. ( 2x - 10 ) + ( 4x +40 ) = 90

Solve for x.

2x - 10 + 4x + 40 = 90

6x + 30 = 90

6x = 90 - 30

6x = 60

x = 10

Solve for Angle A. (by substitition)

<a = 2(10)-10

<a = 20-10

<a = 10°

Solve for Angle C. (by substitution)

<c = 4(10) + 40

<c = 40+40

<c = 80°

Angle B is 90°. A straight line is equal to 180°

So

<a + <b + <c = 180

< b = 180 - (10 + 80)

<b = 90°