Substitution with Two Variables

Question

Answer 1

The equations are

2x + 4y = 8  ------------------------------------>  (1)

5x = 12 + 6y  ----------------------------------------->  (2)

From equation (1)

2x   =   8 - 4y

2x   =   2(4 - 2y)

x   =   4 - 2y

Substitute x = 4 - 2y in equation (2)

5(4 - 2y)   =   12 + 6y

20 - 10y   =   12 + 6y

20 - 12   =   6y + 10y

8   =   16y

y   =   8/16

y  =  1/2

Substitute y = 1/2 in equation (2)

5x   =   12 + 6(1/2)

5x   =   12 + 3

5x   =   15

x   =   15/5

x   =   3

The solution is x = 3 and y = 1/2.