posted by Amanda .
You are using glass tiles to make a picture frame for a square photograph with sides 10 inches long. You want the frame to form a uniform border around the photograph. You have enough tiles to cover 300 square inches. What is the largest possible frame width x.
a. 3.6 inches <-- i think that's right
b. 5 inches
c. 7.3 inches
d. 15 inches
Are the tiles to be used for the border?
let the width of the border be x
so the whole frame = (10+2x)(10+2x)
so area of border = (10+2x)(10+2x) - 100
but (10+2x)(10+2x) - 100 = 300
(10+2x)^2 = 400
10+2x = 20
2x = 10
x = 5