Put 7x-5y+20 into slope intercept form

Which values for a and b will create infinitely many solutions for this system of equations? ax-y=8 2x+y=b

We just started the introduction into circles and i have no idea how to do this.

Someone answer asap for ! michele pushes a box d meters across a floor. she uses a force f, in newtons, to push the box. she pushes the box for t seconds. the formula p = fd/t calculates the power, p, in watts, that it takes for michele to complete the task. solve the formula for d.