Question 1176248
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Here is an alternative to the standard algebraic solution method show by the other tutor.<br>
Consider the least common multiple of the two given times.  The LCM of 1 hour and 1.5 hours is 3 hours.<br>
In 3 hours the number of such lawns Jhon could mow is 3/1 = 3; in 3 hours the number Sam could mow is 3/1.5 = 2.<br>
So in 3 hours the two of them together could mow 3+2=5 lawns.  And that means together they can mow the one lawn in 3/5 hours, or 36 minutes.<br>