write in standard complex form 2+3i \3-4i

The trick here is to rationalize the denominator.  We don't want either an imaginary or a complex number there.

2+3i      3+4i      6+8i+9i - 12      -6 + 17i
------- * ------- = ------------------ = -------------   (answer)
3-4i       3+4i       9+16                    25