math/algebra

solve each of the following systems by substitution. 16) 5x -2y = -5 y - 5x = 3 20) 8x -4y = 16 y = 2x - 4 28) 4x -12y = 5 -x + 3y = -1 Step one: Solve on of the equations for one of the variables. y=2x-4 Step two:Substitute the expression for the variable found in step one into the other equation. 8x-4(2x-4)=16 Step three:Solve the equation from step two to find the value of one variable. Use the distributive property 8x-4(2x-4)=16 8x-8x+16=16 x+16=16 -16 -16 x=0 Step four:Substitute the value found in step three in any equation containing both variables to find the value of the other variable. y=2x-4 y=2(0)-4 y=0-4 y=-4 step five: check the proposed solution in the orginal system. 8(0)-4(-4)=16 0+16=16 16=16 The equation is equal, so it is correct. #28 4x-12y=5 -x+3y=-1 +x +x 3y=-x or -3y=x 4(-3y)-12y=5 4x-12(5)=5 -12y-12y=5 4x-60=5 y=5 +60 +60 4x=65 x=65/4 4(65/4)-12(5)=5 260/4 - 60=5 65 - 60 = 5 5 = 5 it's correct I hope I helped