The expression is
According to subtraction property of equality: if , then
.
(Subtract 2x from each side)
(Commutative property: a + b = b + a)
(Additive invrese property:
)
(Subtract:
)
According to addition property of equality: if a = b, then a + c = b + c.
\ (Add 4 to each side)
(Additive invrese property:
)
(Add:
)
(Divide each side by 7)
(Cancel common terms)
Check:
\To check the solution, substitute in original equation.
(Multiply:
)
(Subtract:
)
(Add:
)
The value of the expression is .