The equations are
\
Equaton(1)
Equaton(2)
Substitute
for y in the Equation (2).

Apply subtraction property of equality; if
, then
.
(Subtract x from each side).
(Subtract:
).
Apply addition property of equality; if
, then
.
(Add 4 to each side)
(Add:
)
(Divide each side by 2)
(Divide:
)
Substitute 4 for x in equation (2).
\
(Add:
)
The solution is
.