18/13 or in simplified form, 1 and 5/13.
I'm terrible at math, so I'm sorry if I'm totally wrong, but I'm assuming you just take the average:
20+28=48m
48/2=24m
On average, it may take them 24m if they work together.
-2 is the answer
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15 inches of ribbon<span> for </span><span>each</span>
