(see image for question)

Answer:
65 degrees
Step-by-step explanation:
triangle exterior angle theorem states that the exterior angle of a triangle is equivilant to the opposite 2 interior angles
apply therorem to get equation:
7x+10= (2x+40)+ (3x)
solve for x
7x+10= 5x+40
2x+10= 40
2x= 30
x=15
angle ABC is 180- (7x+10)
=180 -(7(15)+10)
=180 -( 105+10)
=180 -115
=65
Answer:
65 degrees
Step-by-step explanation:
The angle in question, when added to the corresponding angle outside the triangle, will equal 180 degrees. Therefore:
180 = (7x+10) + ∠ABC
∠ABC = 180 - (7x+10) = 170 - 7x
Now, the sum of the angles inside the triangle will also add to equal 180. To find the measure of ABC, we must first solve the triangle for x:
180 = (170-7x) + (2x+40) + (3x)
180 = 210-2x
x = (180-210)/-2 = 15
Now, input x into ABC to get the degree measure.
ABC = 170 - 7(15) = 170 - 105 = 65 degrees.
Hope this helped!