Question

a 4 in. by 6 in. picture is surrounded by matting that is 3 inches wide all around. find the perimeter of the outside of the matting.

Explanation:

Step1: Calculate new length

The original length is 6 inches. With 3 - inch - wide matting on both sides, the new length $l=6 + 3+3=12$ inches.

Step2: Calculate new width

The original width is 4 inches. With 3 - inch - wide matting on both sides, the new width $w = 4+3 + 3=10$ inches.

Step3: Calculate perimeter

The perimeter formula of a rectangle is $P = 2(l + w)$. Substitute $l = 12$ inches and $w = 10$ inches into the formula: $P=2(12 + 10)=2\times22 = 44$ inches.

Answer:

44 inches