Since addition is commutative, she can add anyway she wants.
(17+51)+(10+13)
(51+10)+(17+13)
Hope this helps.
If r=-3, then it would be -3-12 which equals -15
The answer is 18.
Just replace the x with 2
Each sandwich is toasted for 2 minutes and it takes 3 seconds to flip it.
The first two sandwiches will be toasted in 2 minutes (toasting) and 6 seconds (flipping).
The two will then be switched which will take 10 seconds.
The next two will again take 2 minutes and 6 seconds.
The final sandwich will take 5 seconds to be placed.
The final sandwich will also take 2 minutes to toast and 3 seconds to flip.
Total time:
2 + 2 +2 = 6 minutes
6 + 10 + 6 + 3 = 25 seconds
Total time is 6 minutes and 25 seconds.
