Hint: the sum of the angles is equal to 180 in a triangle. could you make an equation to use that?
3x+13, 7x+2, and 75 are the three angle values. They will sum up to 180.
Steps:
We set the equation to:
3x+13+7x+2+75=180
We can combine some terms
10x+90=180
Then, we isolate x
10x=90
And we divide by 10
x=9
Great! but we are not done yet. We want the measure of angle A, so we need to plug x back into the equation for angle a
3(9)+13
Multiply
27+13
Add
40