2/3 ( 6-9х)=15
3/4 (12-х)=3/2
2/5 ( 8-5х)=1/5

2/3 ( 6-9х)=156-9x=15цел.3/2-9x+6=15×3/2-9x+6=45/2-9x=45-12/2-9х+6-6=45/2-6х=(45-12)×1/-2×9x=33/-18х=11/-6