8（X-2）=2（X+7）8x-16=2x+146x=30x=5一楼的50后面不是乘号是x200X+50X（22-X）=140020x+5x(22-x)=14020x+110x-5x^2=1405x^2-130x+140=0x^2-26x+28=0x^2-26x+169-141=0(x-13)^2=141x-13=根号141或-根号141x=13+根号...