{х+у=10 (100х+70у+у+7х-у=259

To solve this system of equations, let's simplify the second equation first by combining like terms:

100x + 70y + y + 7x - u = 259 107x + 71y - u = 259

Now, we have a system of two equations:

1. x + y = 10
2. 107x + 71y - u = 259

To proceed, we need either another equation or the value of one of the variables.