5(x-4)-7(7-x)-9=12-3(9-x)

问题描述:

5(x-4)-7(7-x)-9=12-3(9-x)

7

5(x-4)-7(7-x)-9=12-3(9-x)
5x-20-49+7x-9=12-27+3x
12x-78=3x-15
12x-3x=78-15
9x=63
x=7

5(x-4)-7(7-x)-9=12-3(9-x)
5x-20-49+7x-9=12-27+3x
5x+7x-3x=12-27+20+49+9
9x=63
x=63÷9
x=7

5X-20-49+7X-9=12-27+3X
5X+7X-3X-9=20+49+12-27+9
9X=63
X=63/9
X=7