Question

what is the answer (4a+5b)×(3a+7b)

Answer 1

this is the answer to your question

Answer 2

the method:
4a(3a+7b) +5b(3a+7b)
=
$12 {a}^{2} + 28ab + 15 ab + 35{b}^{2}$
by grouping,
we have
12a^2+43ab+35b^2

is the answer.