Question

verify that a + b = b + a if A= -8upon7 B=7upon20

Answer 1

a = -8/7
b = 7/20

LHS = a + b 
          =  -8/7 +7/20
           = $\frac{-111}{140}$


RHS = B + A = 7/20 + -8/7
          = $\frac{-111}{140}$

Hence LHS = RHS

Therefore, a + b = b + a