Can someone help me solve this math equation? 16a^2-81b^2?

Question

that's 16a squared minus 81b squared.

thanks! :)

Answer 1

a^2=(81/16)b^2, so square root a^2 = square root (81/16)b^2,

so a=(9/4)b

Answer 2

(4a+9b)(4a-9b)