Macro can finish the puzzle in 3 hours. We can say that her speed for working is 1/3 or 1/3 puzzle per hour.
Now if they work together, this turns into 1 puzzle per hour.
That must mean that Cliff would be doing the other 2/3 of the puzzle while Macro does his 1/3 in that hour. If Cliff has a speed of doing them 2/3 per hour. Then it would take 1 and a half hour to finish 1 whole puzzle.
Rileyflipflop,

= 8

, since she can't buy half a CD, she's limited to no more than 8 CDs. If x = the cost of one CD, then x CDs cost $18x. Since we are limited to $153, our equation looks like... 18x < 153x < 8

Again, since we can't buy half a CD, your answer should actually be... x ≤ 8 since we can buy 8 CDs or fewer.
The correct answer is C. 2 3/8 yd.
I hope that helped you! c:
The missing side would be B = 15