Question 1028038
Call the minutes spent on the treadmill and elliptical, t and e.  Then we write
t + e = 30
12t + 8.5e = 325
Now multiply the top one by 12 and subtract from the bottom one...we get
12t + 8.5e = 325
-(12t + 12e = 360)
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-3.5e = -35
e = 10 minutes on the elliptical which means
t = 20 minutes on the treadmill