3分之x=4分之7-x
问题描述:
3分之x=4分之7-x
答
两边同时乘以 12 得 :
4x = 3(7 - x)
4x = 21 - 3x
4x + 3x = 21
7x = 21
x = 21 ÷ 7
x = 3