列出下列方程,并求出方程的解(1)X的5倍加上60,和是110,求X(2)120比X的2倍多8,求X(3)X的4倍,加上20除160的商,和是128,求X(4)X的5倍比3的5倍多90,求X.
(1)5X+60=110, 5X+60-60=110-60, 5X=50, 5X÷5=50÷5, X=10; (2)2X+8=10, 2X+8-8=10-8, 2X=2, 2X÷2=2÷2, X=1; (3)4X+160÷20=128, 4X+8=128, 4X+8-8=128-8, 4X=120, 4X÷4=120÷4, X=30; (4)5X-3×5=90, 5X-15=90, 5X-15+15=90+15, 5X=105, 5X÷5=105÷5, X=21. |