Answer:
20
Step-by-step explanation:
If 36 boys can conplete a task in 4 hours, then 19.35 boys could do it in 2 and a fourth hours.
You can set up an equation
A fourth of an hour is 15 minutes, so,
36 is to 4 as x is to 2.15, or,
36=4 as X=2.15
Multiply 2.15 by 36 (77.4)
77.4 divided by 4= 19.35.
Of course, you cannot have 19.35 boys, so there must be 20.
Hope this helps!