The cost of a calculator is $2.50 less than five times the cost of a notebook. If Jordan purchases one calculator and one notebook, the total cost is $20.

Question

I need help like now aha because I need to find the cost of the calculator. c = cost of the calculator and n = cost of the notebook. i have one equation to find c which is 5n - 2.50 = c but i need n to complete it.

Answer 1

Hello Jennifer

 

You got the 1st equation correct,

 

Eq 1)  c = 5n - 2.50

 

Equation 2) is c + n = 20 (f Jordan purchases one calculator and one notebook, the total cost is $20).

 

Substitute c = 5n - 2.50 into Eq 2), you get

 

5n - 2.50 + n = 20

 

6n = 22.50

 

n = 3.75

 

c = 5n - 2.50

 

   = 5(3.75) - 2.50

 

   = 18.75 - 2.50  = 16.25

 

Therefore, 1 notebook is $3.75 and 1 calculator is $16.25.

 

To confirm, c + n = $20

 

16.25 + 3.75 = $20 !!

Answer 2

Let c= cost of the calculator

     n= cost of the notebook

Eq. I:  c=5n-2.50

Eq. II: c+n=20

Use either the substitution method or elimination method to solve for one of the variables then put that value into either equation and solve for the other variable. (HINT: use substitution method; you already know what c is terms of n (Eq. I)).