Question

Please help me with this

Answer 1

Step-by-step explanation:

such an equation is a simple linear function :

y = ax + b

b is in this case the flat fee, and a (the slope) drives the incline of the function for various numbers of students x.

our job is now to find the correct a and b values.

we do this by using the informative we have and create 2 equations for a and b, and then we solve this system.

132.5 = a×25 + b

145 = a×30 + b

now, we can use a little trick and simply subtract the whole first equation from the second equation.

145 = a×30 + b

- 132.5 = a×25 + b

------------------------------

12.5 = a×5 + 0

5a = 12.5

a = 2.5

with this we go into one of the original equations, e.g. the second one :

145 = 2.5×30 + b = 75 + b

70 = b

so, it full equation is

y = 2.5x + 70

the costs for 85 students are

y = 2.5×85 + 70 = 212.5 + 70 = $282.50