Answer
$$(x-7)(x+5)=13$$
Work Step by Step
We can call our unknown number "$x$".
A product means a multiplication.
A number decreased by 7 can be written as $x-7$.
The same number increased by 5 can be written as $x+5$.
(Remember to add the parenthesis to the multiplication.)
So,
$(x-7)(x+5)=13$
