Answer:
I found:
x=-3
y=5
Explanation: I would multiply the first equation by −4 and the second by 3 and add together the two equations (in columns):
{−12x−28y=−104
{12x+15y=39
0−13y=−65
So: y=65/13=5
Substitute back this value into the first equation:
3x+7⋅5=26
3x=26−35=−9
x=−9/3=−3
