How to solve the problem of synchronizing 40 and 4 1 surface in the first volume of the fifth grade of People's Education Press?
(X- 12)÷4 = 4.5 4.5X+X = 23. 1 12X+24X- 15X = 147
x- 12 = 18 5.5x = 23. 1 2 1x = 147
x =30 x=4.2 x =7
Hope to adopt opinions.