Do you remember how to find the equation of a line when you know two points on the line ? Well, that little table gives you FIVE points on the line, and in case some students didn't notice that, the table even labels the columns 'x' and 'y' as a hint. With 5 points given, there are 20 different ways to find the equation of the line. Get to work.
Answer:
4800
Step-by-step explanation:
x is the number of total students
x * 9/20 = number of female students
x * 9/20 = 2160
Multiply each side by 20/9
x * 9/20 * 20/9 = 2160 * 20/9
x =4800
Min Cost = $12,200
Number of buses needed = 7
Number of vans needed = 24
Because if you multiply 2 different irrational numbers (like the following)

You will get an irrational answer.
BUT
if you multiply the same square root (which are both irrational, you get a rational number)
You should start with an equation.

The 'x' represents the week.
so now, we have to subtract 125 from the total amount which is 245.

now we have

to find 'x', we must divide 15 on each side

we are now left with

that means Sierra will have 8 weeks until she has enough money to buy the bike