Question

A triangle has ∠A, ∠B, and ∠C.

∠B is 20° more than ∠A.
∠C is double ∠B.
How big is ∠A?

Answer 1

Let angle A be x degrees
Angle B=(x+20) degrees
Angle C=2(x+20)=(2x+40) degrees

angle A+angle B+angle C=180 degrees(sum of the angles of a triangle=180 degrees)
x+x+20+2x+40=180
5x+60=180
5x=180-60
5x=120
x=120/5
x=40 degrees
A=40 degrees

Hope this helps!

Answer 2

30°

Explanation:

∠A + ∠B + ∠C = 180

∠B = ∠A + 20

∠C = 2 * ∠B

<A + (∠A + 20) + (2 * ∠B) = 180

<A + (∠A + 20) + (2 * (∠A + 20)) = 180

<A + (∠A + 20) + 2∠A + 40 = 180

4∠A + 60 = 180

4∠A = 120

∠A = 30