解:
解方程, 此方程的解为x = 43/10,【即x = 4.3】
12.3 + 5x = 33.8
(12×10+3)/10 + 5x = (33×10+8)/10
123/10 + 5x = 338/10
5x = 338/10 - 123/10
5x = 215/10
5x = 43/2
x = 43/2 ÷ 5
x = 43/2 × 1/5
x = 43/10
∴x = 4.3
经检验,12.3 + 5 × 4.3 = 33.8符合题意
答:此方程的解为x = 43/10,【即x = 4.3】