Answer:
x = 15
Explanation:
∠B = 180 - 110
= 70 degrees
Since all the angles in a triangle add up to 180 we can solve for x like this:
180 = (3x + 30) + (x+20) + 70
Step 1 : Collect like terms
180 = 4x + 120
Step 2 : Move the terms to isolate 4x
-4x = 120 - 180
-4x = -60
Step 3 : Divide both sides by -4 which gives us:
X = 15
We can check to see if this works
3(15) + 30 = 75
15 + 30 = 35
Add all values up
75 + 35 + 70 = 180 (the sum of all angles in any triangle)
Hope this helps!