Question

What must be added to - 21a + b - 9ab to get the sum 18 a - 31b+ ab - 32?

Answer 1

here is your answer thank you

Answer 2

-21a+b-9ab + x = 18a-31b+ab-32
x=18a-31b+ab-32 -(-21a+b-9ab)
x= 18a-31b+ab-32 + 21a-b+9ab
x=18a+21a-31b-b+ab+9ab-32
x=39a-32b+10ab-32