Answer: 50 in²
Explanation: Remember that the formula for the area of a rectangle is length · width so we need to find the width of the rectangle.
To find the width of the rectangle, let's use our formula
for the perimeter of a rectangle which is 2l + 2w.
Since we know that the perimeter of the rectangle is 30 inches and the length of the rectangle is 10 inches, we have 30 = 2(10) + 2w.
Simplifying on the right side gives us 30 = 20 + 2w.
Now subtract 20 from both sides to get 10 = 2w.
Finally, dividing both sides by 2, we find that 5 = w.
So the width of the rectangle is 5 inches and remember
that the length of the rectangle is 10 inches.
So the area of the rectangle, l · w, is 10 · 5 or 50 in².
