Respuesta :
SOLUTION
The first machine is 8 calories per minute.
The second machine is 6 calories per minute.
This allows us to set up a system of equations. The first equation will be for calories burned:
8x + 6y = 300.............1
'x' is minutes on the 8 calories per minute machine; 'y' is minutes on the 6 calories per minute machine.
A second equation simply shows that the total minutes add up to 40:
x + y = 40...................2
Now that we have two equations, we can solve them using the substitution method of the simultaneous equation.
[tex]\begin{gathered} 8x+6y=300\ldots\ldots\ldots\text{.}.1 \\ x+y=40\ldots\ldots\ldots\ldots2 \end{gathered}[/tex]Isolate 'x' from equation 2
[tex]x=40-y\ldots\ldots\ldots3[/tex]Substitute x = 40-y into equation 1
[tex]\begin{gathered} 8(40-y)+6y=300 \\ 320-8y+6y=300 \\ 320-2y=300 \\ \text{Collect like terms } \\ 320-300=2y \\ 20=2y \\ \text{Divide both sides by 2} \\ \frac{20}{2}=\frac{2y}{2} \\ 10=y \\ \therefore y=10 \end{gathered}[/tex]Now, substitute y = 10 into equation 3 and evaluate for x
[tex]\begin{gathered} x=40-y \\ x=40-10=30 \\ \therefore x=30 \end{gathered}[/tex]Hence, you should spend 30 minutes on machine 1 and 10 minutes on machine 2.
Final answers
[tex]\begin{gathered} \text{Elliptical trainer, x = 30minutes} \\ \text{Stationary bike, y = 10minutes} \end{gathered}[/tex]