Py +7 = 6y + qp
Solve the equation for y
To solve the equation for y we need to get y alone
Py +7 = 6y + qp
Subtract 6y from both sides
Py - 6y +7 = + qp
Subtract 7 from both sides
Py - 6y = + qp - 7
Now factor out y
(P - 6)y = qp - 7
Divide by P - 6 from both sides

150 + 20x, where x is the number of cellphones sold