The equations are
\ Equation (1)
Equation (2)
Multiply the equation (2) by 2.
\ Equation (3)
Eliminate the variable s by subtracting the Equation (1) from Equation (3)
\ (Subtract the corresponding columns)
Apply division property of equality: if a = b, then.
(Divide each side by 5)
(Cancel common terms)
(Divide:
)
Substitute in equation (1).
Apply subtraction property of equality: if a = b, then .
(Subtract 4 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 4)
(Cancel common terms)
(Divide:
)
The solution is
The solution is .