check the picture below, you can pretty much count the units off the grid.
recall that A = (1/2)bh.
This is the concept of algebra, we solve the question as follows:
The cost of renting a camping tent is y
The number of days is x
cost is proportional to number of days, thus:
yαx
y=kx
where k is the constant of proportionality.
If y=$56 when x=7 days, then:
56=7k
hence:
k=56/7=8
therefore:
y=kx will be:
y=8x
the equation in slope intercept form which is y=mx+c is y=8x. In our case c=0 because there was no initial payments required to rent apart from the daily charges.
The function f(x) is a function of the variable x.
To solve the function for x = 30, just plug in 30 for x.
14 - 0.5(30) = -1
f(30) = -1
25, 7*4 = 28 32-28=4 and 42/6=7*3 = 21 + 4 = 25