Question

solve this please.... by factorising it..

Answer 1

$<b>$ hey mate

your answer is given in the attachment

$\huge\boxed{8000}$

hope it helps you

Answer 2

by using formula a
${a}^{2} - {b}^{2} = (a - b)(a + b)$
(405-395)(405+395)=10×800=8000