2x+y=4 2·6+(−8)=?4
12−8=?4
4=4
What do you substitute for x and y in the first equation?

Substitute 6 for x and −8 for y in the first equation.

Perform the multiplication first.
When the left side of the equation is simplified, a true statement results.

x+3y=−20
6+3·(−8)=?−20

6−24=?−20
−18≠−20
What do you substitute for x and y in the second equation?

Substitute 6 for x and −8 for y in the second equation.

Perform the multiplication first.
When the left side of the equation is simplified, a false statement results.