5 would be the dependent variable because the number 5 depends on how many greeting cards are bought.
Answer:
Question 13: For age groups y=1 and y=1.3 response is 8 microseconds.
Question 14: The club was making a loss between 11.28 and 4.88 years.
Step-by-step explanation:
Question 13:
The age group y for which the response rate R is 8 microseconds is given by the solution of the equation

We graph this equation and find the solutions to be

Since only positive solutions for y are valid in the real world we take only those.
Thus only for age groups y=1 and y=1.3 the response is 8 microseconds.
Question 14:
The footbal club is making a loss when 
Or

We graph this inequality and find the solutions to be
and 
Since in the real world only positive values for t are valid, we take the the second solution to be true.
Thus the club was making a loss in years 
If you would like to know the price Jay can pay the manufacturer for the blow up bed, you can calculate this using the following steps:
100% + 40% = 140%
140% of x is $299
140% * x = 299
140/100 * x = 299 /*100/140
x = 299 * 100 / 140
x = $213.6
40% of $213.6 = 40% * 213.6 = 40/100 * 213.6 = 85.44
$213.6 + $85.44 = $299
The correct result would be $213.6.