Two cars start at the same point and travel in the same direction at the average speeds of 70 miles per hour, and 40 miles per hour . determine after how much time ( in hours) the two cars will be 105 miles apart

You can check it by solving it in your head.  They are separating at the rate of 55-40 or 15 miles per hour.  So in 1 hour or 60 minutes they'll be 15 miles apart, so in 20 minutes they'll be 5 miles apart, so in 40 minutes they'll be 10 miles apart.  So it has to be 40 minutes.

Step-by-step explanation:

55t-40t=10

15t=10

15t/15=10/15

2/3

40 Minutes

why do wages differ across industries

step-by-step explanation :

micro economists are concerned with economics on an industry or individual firm basis.

macro economists are concerned with national and international level

he spend 5.1 minutes chatting with his friends.

step-by-step explanation:

2/5+1/2=9/10

6/1-9/10=5.1