Respuesta :
Alright, lets get started.
If Matthew wants to complete packages at an average rate of at least 39 packages per hour.
And they worked 4 hrs only due to picnic, yesterday, it means they have to make [tex] 39*4 = 156 [/tex] packages.
But they made only 112 packages means they are short of [tex] 156 - 112 = 44 [/tex] packages.
Suppose they are working today t hrs, and his department will complete 43 packages per hour today.
It means they are going to make 43 t packages today.
This 43 t packages includes those 44 too , which they are short of yesterday due to picnic.
So, average will be
[tex] \frac{43 t - 44}{t} = 39 [/tex] (39 average given in question)
Cross multiplying
[tex] 39 t = 43 t - 44 [/tex]
Adding 44 in both sides
[tex] 39 t + 44 = 43 t - 44 + 44 [/tex]
[tex] 43 t = 39 t + 44 [/tex]
Subtracting 39 t in both sides
[tex] 43 t - 39 t = 39 t + 44 - 39 t [/tex]
[tex] 4t = 44 [/tex]
Dividing 4 in both sides
t = 11 hrs
Hence they have to woth 11 hrs today : Answer
Hope it will help :)