text: Do both of those equations relate? Then use Systems of Equations:\n\n2x+3y=7\n5x-y=9\n\nMultiply one of the equations by a factor that will lead to one of the variables dropping out. I am multiplying the second one by 3.\n\n2x+3y=7\n15x-3y=27\n\nNow add the two equations up, it is easiest to do when they are on top of each other.\n\n2x+3y=7\n15x-3y=27\nBecomes:\n17x = 34\n\nThen solve for x\n17x = 34\nx = 2\n\nNow that you know x you can plug x into one of the equations to find y. I like the second one better, since y isn't multiplied by anything.\n\n5x-y=9\nPut x=2 in\n10 - y = 9\n-y = -1\ny = 1\n\nSo, x=2 and y=1\n\nThis method works for all the kinds of equations like this. I am not sure what you mean by a formula?