The sum of interior angles in a triangle are 180 degrees. Angle B and C are congruent. Angle B is twenty less than angle A. Write and solve a system of equations using substitution.

A = 73.33

B = 53.33

C = 53.33

Step-by-step explanation:

Mathematically, adding the 3 angles would equal 180

Thus;

A + B + C = 180 •••••(i)

Since B and C are congruent, that means they are equal ( we are looking at isosceles triangle)

B = C •••••••••(ii)

Lastly;

B = A -20 ••••••••(iii)

Make a substitution in equation 1;

A + A -20 + A -20 = 180

Since B = C ; C also is A-20

3A -40 = 180

3A = 220

A = 220/3 = 73.33

B = C = A -20 = 73.33 -20 = 53.33