Dave and mary depart from the bus station at 10 am traveling in opposite directions. dave's bus is going 40 miles per hour and mary's is going 50 miles per hour. at what time will they be 270 miles apart?

  In 3 hours they will be 270 miles apart.

Since Dave and Mary are going opposite directions every hour mary will be moving 50 miles away and Dave will be moving 40 miles away meaning they will move 90 miles away from each other every hour. So 270 is 90 times three so in three hours they will be 270 miles away so at 1 pm they will be 270 miles apart.

First, think of what you know. you know that the number t the end of the equation will need to be subtracted because it is the money he lost from buying the lawn mower. and your first two weeks have negative profit, so that tells you that c and d are wrong. now you can plug any of the weeks into a and b to see which one works. i'll start with plugging week 1 into a.this isn't right because it says your answer for week one should be -90.so now we need to try the same thing with b.this one got you the right answer, (sometimes if you only check with one of the weeks multiple will work so you need to check with more of the weeks, but it worked out fine here)this means that b is the correct answer.let me know if you need more clarification. i hope this : )