I have angle b its 40 but i don't remember how to set the equation up

Question

For a given triangle, the measure of angle A is 10° less than three times the measure of angle B. The measure of angle C is one-fifth the sum of the measures of angles A and B. Knowing that the sum of the measures of the angles of a triangle equals 180°, find the measure of each angle.

Answer 1

B represents the measure of B

3B - 10° represents the measure of A

(0.2)(B + 3B - 10°) represents the measure of C

 

B + (3B - 10°) + (0.2)(B + 3B - 10°) = 180°

 

Can you solve for B and answer?

Answer 2

JJ, it's simultaneous equations:

 

A = 3B - 10

 

C = (A + B)/5, so C = (3B - 10 + B)/5

 

A + B + C = 180

 

Use substitution to solve.  Can you do it from here?

 

 

Answer 3

Set up three equations:

 

A = 3B - 10

C = (1/5)*(A + B)

A + B + C = 180

 

Then solve the system of equations to determine the angles A, B, and C.