Henry is using a total of 16 ft. of lumber to make a bookcase. The left and right sides of the bookcase are each 4 ft. high. The top, bottom, and two shelves are all the same length, labeled S. How long is each shelf?

Each shelf is 2ft

Step-by-step explanation:

16 = (2 x 4) + 4s

16 = 8 + 4s

8 = 4s (subtract 8 from both sides)

8/4 = 4s/4 (divide both sides by 4)

2 = s

7 weeks

step-by-step explanation:

convert each fraction to the least common multiple of 20, so 3/4 = 15/20 & 1/10 = 2/20, then divide 15 by 2 and you get a little over 7, so the food will last 7 weeks.

the solution is 12x-6y