Question

A 5” x 7” picture needs a frame whose width is the same on all four sides. If the frame’s perimeter is 28”, what should be the width (x) of the frame?

A) Half of an inch
B) Quarter of an inch
C) Two inches
D) One inch

Answer 1

Half an inch

Explanation:

Perimeter of the frame = 28 inches

Length fo the frame = 7 + x + x = (7 + 2x) inches

Width of the frame = 5 + x + x = (5 + 2x) inches

Perimeter of a rectangle is given as: 2(length) + 2(width)

Therefore:

28 = 2(7 + 2x) + 2(5 + 2x)

Solve for x

28 = 2*7 + 2*2x + 2*5 + 2*2x

28 = 14 + 4x + 10 + 4x

Collect like terms

28 = 14 + 10 + 4x + 4x

28 = 24 + 8x

Subtract 24 from both sides

28 - 24 = 24 + 8x - 24

4 = 8x

Divide both sides by 8

4/8 = 8x/8

½ = x

Width of the frame = x = ½ of an inch