The expression is .
(Write the equation)
(Subtract 42 from each side)
(Subtract:
)
(Apply additive identity property:
)
(Divide each side by 13)
(Cancel common terms)
(Divide:
)
The solution is 2.
Check:
\Substitute in the equation.
(Write the equation)
(Substitute
)
(Multiply:
)
(Add:
)
The solution was checked.
The solution is .