Linear Equation Question

Question

Mary and Dave bought the same jump drives and portable hard drives for their classes. Dave spent $4248.95 on 20 jump drives and 25 portable drives. Mary spent $5148.70 on 25 jump drives and 30 portable hard drives. What is the cost of one jump drive, and what is the cost of one portable hard drive?

 

 

 

Linear equations math question I don't understand

Answer 1

x = cost of 1 jump drive

y = cost of 1 portable drive

 

The given information translates into algebra as

 

20x + 25y = 4248.95

25x + 30y = 5148.70

 

Now solve for x and y using elimination, matrix methods, or Cramer's rule. Can you finish from here?

 

x = 49.96

y = 129.99

Answer 2

j = cost of jump drive

p = cost of portable drive

 

20j + 25p = 4248.95

25j + 30p = 5148.70

 

Let's use elimination to solve the system of equations.

Multiply the 1st equation by 5

Multiply the 2nd equation by -4

Add the resulting equations to eliminate the j variable.

 

This will leave an equation with only one variable which can be

solved to find the cost of p... a portable hard drive.

 

From there, plug that value into one of the original equations

and solve it for j to find the cost of a jump drive.