3(5a-2)-4(3a-3)=15a-6-12a+12=3a+6 不懂可追问,有帮助请采纳,谢谢!
3(5a-2)-4(3a-3)=15a-6-12a+12=3a+6
原式=15a-6-12a+12=3a+6
=(3×5a-3×2)-(4×3a-4×3)=(15a-6)-(12a-12)=15a-6-12a+12=3a+6