How do you solve 3x+2y=27 and x=y+4 using substitution?

Mar 5, 2016

x = 7 , y = 3

Explanation:

One of the equations x = y + 4 , gives x in terms of y.

This means it can be substituted directly into 3x + 2y = 27.

hence : 3( y + 4 ) + 2y = 27 . We now have an equation in 1 variable.

expanding brackets : 3y + 12 + 2y = 27

collecting y terms on left and numbers on right gives:

5y = 27 - 12 → 5y = 15 → y = 3

now x = y+4 → x = 3 + 4 = 7