Answer
The photo is 7 by 12.
Work Step by Step
Note, the 5 step process is as follows:
(1) Familiarize yourself with the problem.
(2) Translate the problem into Algebra.
(3) Solve.
(4) Check. Note, if we want to check a solution, we would plug it back into the equation and check that the equation yields a true statement.
(5) State the answer.
After becoming familiar with the problem, we find:
$$(w)(w+5)=84 \\ w^2+5w-84=0 \\ w_{1,\:2}=\frac{-5\pm \sqrt{5^2-4\cdot \:1\left(-84\right)}}{2\cdot \:1} \\ w=7\ \text{(Since only positive solutions count).} \\ l=7+5=12$$
The photo is 7 by 12.
