Let x represent the # of 2-hour days and y the # of 3-hour days. Jimmy's study was spread over 10 days. Thus, x + y must sum up to 10. Also, 2x + 3y must sum up to 22 hours.Our system now looks like this:
x + y = 10
2x + 3y = 22
Multiply the first equation by -2: -2x - 2y = -20 Add the 2nd equation to this:
-2x - 2y = -20
2x + 3y = 22
------------------ y = 2 So Jimmy had 2 3-hour study days and 8 2-hour study days.
Note how these figures add up to 22: 6 + 16 = 22
Hope that help!
