Question

1 а+(17+b) 2 (а+26)+b 3 (b+а)+9 4 а+(b+13)

Answer 1

17ab.  26 ab .  9ab . 13 ab

Answer 2

A + ( 17 + B ) = A + B + 17 ;
( A + 26 ) + B = A + B + 26 ;
( B + A ) + 9 = A + B + 9 ;
A + ( B + 13 ) = A + B + 13