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Question

A gym has two machines you want to use. An elliptical trainer that burns 8 calories per minute, and a stationary bike that burns 6 calories per minute. You have 40 minutes to exercise at the gym, and you want to burn 300 calories total using both machines. How much time should you spend on each machine? 

Answer 1

x is the time you spend on the elliptical ( in minutes)

y is the time you spend on the stationary bike (in minutes)

8x + 6y = 300

x + y = 40

multiple both sides of the equation (x + y = 40) by -8 so we can cancel the X

8x + 6y = 300

-8x - 8y = -320

add the two equations together and get:

0-2y = -20

y = 10

plug 10 back into first equation and get

8x +60 = 300

8x = 240

x = 30

Spend 10 minutes on the stationary bike and 30 minutes on the elliptical

let me know if questions

Julie

Answer 2

8x+6y=300

Shortest time span: x=37; y=2/3