With the information given, you don't know anything about (5x-7), except that it's equal to (5x-7). If you could also get an actual number that it's equal to, then you could figure out the value of...
Your answer is x = 1 & y = -2 Given Equations: 2x-y=4 y=5x-7 Using Substitution Substitute y for 5x-7 to simplify the equation to only 1 variable. 2x-(5x-7)=4 Simplify a. 2x-5x+7=4 b. -3x=-3 c....