Rachel fills 13 water bottles per hour, so she contributes 13R. Alyssa fills 15 bottles an hour, so she contributes 15A, plus 5 for the additional water bottles filled. Thus, the full expression is:
13R+15A+5
You have to do substitution in both sides e) (-4,2)
Answer: $6.50
If the number is below 5 (so 1-4) you round down. If its above 5 (5-9), you round up.
E.G. 78.89
Round this to the nearest 10th, you'll get 78.90
Learn the common vocabulary for multiplication, division, subtraction and addition it will help you understand what they mean in the written expression