144, its just repeated addition... 12+12+12+12+12+12+12+12+12+12+12+12=144
If Ms. Callahan has 24 feet of fencing, and she is building a pen, the PERIMETER of the pen must be 24 feet. The perimeter is basically the distance around a figure. The perimeter of a rectangle is equal to length plus width plus length plus width, AKA l+w+l+w, or P=2l+2w. In a rectangle, two pairs of sides are of equal length--so the two lengths and the two widths must be equal.
So, the formula is P=2l+2w. P, the perimeter, is 24, so 24=2l+2w. Let's try some values for l and see what we get for w. If the length is 1, l=1. 24=(2*1)+2w. 24=2+2w. 22=2w. w=11. So if length is 1 foot, width is 11 feet.
What if l=2? 24=(2*2)+2w. 24=4+2w. 2w=20. w=10. If l=2, w=10. And l=3? 24=(2*3)+2w. 24=6+2w. 18=2w. w=9. If l=3, w=9. Do you see a pattern? Every time we add 1 to l, we subtract 1 from w. So if l=4, w=8. If l=5, w=7. If l=6, w=6. Here, we start getting similar answers: if l=7, w=5. If l=8, w=4. Since we already know these values work, it doesn't matter whether we call it length or width. So, our answers are below.
Answer: Ms Callahan can make a pen with a length of 1 foot and a width of 11 feet, a length of 2 feet and a width of 10 feet, a length of 3 feet and a width of 9 feet, a length of 4 feet and a width of 8 feet, a length of 5 feet and a width of 7 feet, or a length of 6 feet and a width of 6 feet.
You can prove the proofs by showing your work to prove the proofs.
When multiplying by multiples of 10, move the decimal place one place over to the right. 44,000 becomes 440,000.
