Answer:
x = 40
Step-by-step explanation:
The three angles in a triangle add to 180 degrees
x + 30 + (3x-10) = 180
Combine like terms
4x +20 = 180
Subtract 20 from each side
4x+20-20 = 180-20
4x= 160
Divide each side by 4
4x/4 =160/4
