The equation is .
Apply distributive property: .
Apply distributive property: .
(Multiply:
)
Apply subtraction property of equality: If a = b then .
(Subtract 40 from each side)
(Apply additive inverse property:
)
(Apply additive identity property:
)
(Subtract:
)
(Subtract 3d from each side)
Apply commutative property of addition: .
(Apply additive inverse property:
)
(Apply additive identity property:
)
(Subtract:
)
Apply division property of equality: If a = b then
(Divide each side by 2)
(Cancel common terms)
(Divide:
)
Check:
\To substitute in
.
(Substitute
)
(Subtract:
)
(Add:
)
(Multiply:
)
The equality is true
The solution is .