根据题意可得:
(1)2.5X+34=49,
2.5X+34-34=49-34,
2.5X=15,
2.5X÷2.5=15÷2.5,
X=6;
(2)3.1X+4X=1.42,
7.1X=1.42,
7.1X÷7.1=1.42÷7.1,
X=2;
(3)4X+3×9=29,
4X+27=29,
4X+27-27=29-27,
4X=2,
4X÷4=2÷4,
X=0.5.
根据题意可得:
(1)2.5X+34=49,
2.5X+34-34=49-34,
2.5X=15,
2.5X÷2.5=15÷2.5,
X=6;
(2)3.1X+4X=1.42,
7.1X=1.42,
7.1X÷7.1=1.42÷7.1,
X=2;
(3)4X+3×9=29,
4X+27=29,
4X+27-27=29-27,
4X=2,
4X÷4=2÷4,
X=0.5.