(1)
5(x+1.1)=15.5
x+1.1=15.5/5
x+1.1=3.1
x=3.1-1.1
x=2
(2)2.5x=15
x=15/2.5
x=6
(3)
36x+25x=12.2
61x=12.2
x=12.2/61
x=0.2
5x+1.1x=15.5
(1)5x+5.5=15.5
5x=10
x=2
(2) x=15/2.5=6
(3)61x=12.2
x=0.2
5(x+1.1)=15.5
5x+5.5=15.5
5x=10
x=2
2.5x=15
x=15/2.5
x=6
36x+25x=12.2
61x=12.2
x=12.2/61
x=0.2
(记得采纳哦)