(7x-10y)-(-10y-5x)=?

(7x-10y)-(-10y-5x)=?

(7x-10y)-(-10y-5x)=7x-10y+10y+5x=12x

5x-3y=4 7x+3y=-16

5x-3y=4 ①
7x+3y=-16 ②
① + 2, get it
12x=-12
Substituting x = - 1 into (1), we get
y=-3
The solutions of the original equations are x = - 1, y = - 3

Solution of equation. X-38 = 12 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 4-0.7x = 3.79.7x

（1）x-38=12      x-38+38=12+38           x=78；（2）4-0.7x=3.79   4-0.7x+0.7x=3.79+0.7x     3.79+0.7x=43.79+0.7x-3.79=4-3.79          0.7x=0.21     0.7x÷0.7=0.21÷0.7              x=0.3．