First equation: 9x + 7y = 1
Second Equation: -3x + y = 13
Multiply the second equation by 3
-3x + y = 13 * 3 = -9x +3y = 39
Now add the first and multiplied second equation together:
10y = 40
Divide both sides by 10:
y = 4
Now you have a value for y, replace y in the first equation and solve for x:
9x +7(4) = 1
9x + 28 = 1
Subtract 28 from both sides:
9x = -27
Divide both sides by 9:
x = -3
The solution is (-3,4)