If you would like to solve the system of equations, you can do this using the following steps:
y = 7 * x + 43
y = 2 * x + 13
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7 * x + 43 = 2 * x + 13
7 * x - 2 * x = 13 - 43
5 * x = - 30 /5
x = - 30 / 5
x = - 6
y = 7 * x + 43 = 7 * (- 6) + 43 = - 42 + 43 = 1