Find the solution to the system by the substitution method. 3x – 5y = 7 x – 4y = 7 3x  5y = 7
x  4y = 7 x = 4y  7 {added 4y to each side of bottom equation} 3(4y  7)  5y = 7 {substituted (4y  7), in for x, into top equation} 12y  21  5y = 7 {used distributive property} 7y  21 = 7 {combined like terms} 7y = 28 {added 21 to each side} y = 4 {divided each side by 7} x = 4y  7 {new bottom equation} x = 4(4)  7 {substituted 4, in for y, into new bottom equation} x = 16  7 {multiplied} x = 9 {subtracted} x = 9 and y = 4 By the way, that means the point (9,4) is the point of intersection of the two lines when they are graphed on a coordinate plane.  Algebra House
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