(1)52-x=15
52-x+x=15+x
x+15=52
x+15-15=52-15
x=37;
(2)91÷x=1.3
91÷x×x=1.3×x
1.3x=91
1.3x÷1.3=91÷1.3
x=70;
(3)5x+6x=44
11x=44
11x÷11=44÷11
x=4;
(4)x+8.3=10.7
x+8.3-8.3=10.7-8.3
x=2.4;
(5)6x-0.6=12
6x-0.6+0.6=12+0.6
6x=12.6
6x÷6=12.6÷6
x=2.1;
(6)(8+x)×4=48
(8+x)×4÷4=48÷4
8+x=12
8+x-8=12-8
x=4.