If a+2b/a-2b=3, determine the value of a+3b/a-3b

Answer 1

I am sure you meant to say
(a+2b)/(a-2b) = 3

If so, then
3a-6b = a+2b
2a=8b
a=4b

then (a+3b)/(a-3b)
= (4b+3b)/(4b-3b)
= 7b/b
= 7