（x-9.4)*4.5=30.6
x-9.4=6.8
x=16.2
9*3-1.7x=13.4
-1.7x=4.1
x=41/17
(x+3.7)*2.8=14.56
x+3.7=5.2
x=1.5
(x-9.4)*4.5=30.6
x-.9.4=6.8
x=16.2
6.8x=8.33*9+4.7x
6.8x-4.7x=8.33*9
2.1x=8.33*9
x=2499/70