Answer:

Step-by-step explanation:
If you add a number that is negative, you are basically subtracting it.
This means that

Since they both have the same denominator, you can easily subtract the fractions: 
Answer:
Mark’s method is correct, because even though it is impossible to deliver mail to 1.2 houses in a minute, 1.2 represents the unit rate of houses per minute.
Step-by-step explanation:
Just took the test.
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Answer:
5.8
Step-by-step explanation: