Question

The perimeter of a triangle is 7a - 11b. If two of its sides are 2a + b and a - 9b, what is the third side?

Answer 1

P = 7a -11b

side _1 = 2a +b
side_2 = a -9b

side_3 = P -(side_1 +side_2)

side_3 = 7a -11b -(2a +b +a -9b) = 7a -11b -(3a -8b)

side_3 = 7a -11b -3a +8b = 4a -3b

side_3 = 4a -3b

hope helped