The system of equations are
and
.
Equation (1)
Equation (2)
Solve the second equation for x.
\Apply addition property of equality: Add 3y to each side.
\
Rearrange the terms using commutative property of addition: a + b = b + a.
\
(Apply additive inverse property:
)
(Apply additive identity property:
)
Apply multiplication property of equality: Multiply each side by negative 1.
\
(Product of two same signs is positive)
Substitute
in
.

Distribute terms using distributive property: a( b + c ) = ab + ac.
\
(Multiply:
)
(Apply additive inverse property:
)
(Apply additive identity property:
)
Because the equation 18 = 18 is always true, there are an infinite number of solutions. \ \
The system has inifinite solutions.