Please help !!! URGENT svp

4 a  (3x-9)(2x-8)=0
6x²-24x-18x+72=0
6x²-42x+72=0
Δ=b²-4ac
=42²-4×6×72=36
√Δ=√36=6
x=(42-6)÷(2×6)=3
x=(42+6)÷(2×6)=4
solution : 3  4