Question

Xiao's teacher asked him to rewrite the sum 60+90 as the product of the GCF of the two numbers and a sum. Xiao wrote 3(20+30). What mistake did Xiao make? How should he have written the sum?

Answer 1

$The\ mistake:GCF(60;\ 90)\ isn't\ 3\ just\ 30.\\\\Correct\ answer:60+90=30(2+3)$