college algebra
posted by Anonymous .
A bookcase is to be constructed as shown in the figure below. The height of the bookcase is 4 feet longer than the length of a shelf. If 20 feet of lumber is available for the entire unit (including the shelves, but NOT the back of the bookcase), find the length and height of the unit

h = l + 4
Assume a box, but the two shelves will not necessarily be at the top and bottom of the box. Find the perimeter.
2h + 2l = 20
Substitute l + 4 for h in the second equation and solve for l. Put that value in the first equation to find h. Check by putting both values into the second equation. 
find the ratio of whole numbers that is equivaletion to the radio of 16 ft to 10 yd.