Answer: -32
You are taking away from "withdrawal"
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.
All the primes of 24 is 1,2,3,4,6,8,12,and 24
Amy: (3 pages/min)(x min) + 9 pages
Sam: (2 pages/min)(x min) + 47 pages
Equate these: 3x+9 = 2x + 47
Then x = 38. The two friends will have covered the same number of pages after 38 minutes. How many pages would that be? 3(38)+9 = 123 pages.
Given that they follow the format for straight lines and are therefore straight lines, they would only intersect once and that would be at (0,1) where they both have a y intersect.
Hope this helps :)