Answer: 
Step-by-step explanation:
The first thing you must remember is the mulplication of signs. You know that:

You can observe that the number inside the parentheses is positive (+) and the sign that is outside the parentheses is negative (-), therefore, when you multiply these signs you get a negative sign (-). Then you get:

Now, you need to add these numbers. And the result obtained is:

The numerator and denominator need parentheses for clarity.
(4/5)/(2/3)=4/5*3/2=12/10=1 1/5
two fractions dividing is the same as two fractions multiplying with the second fraction flipped around
1 1/5 yards per second
You're going to want to take the total, which is $353.00 and subtract the initial cost, which is $84.00, the number now should be $269. Using that total divide it by $68.00, there you should find your answer of about 4 hours. The precise answer is 3.99588235. But you would round that to 4 hours.