Ken walked 300 feet at 4ft/s and then walked 250 feet at 5ft/s .
how long did he walk?
a.
50 seconds
b.
125 seconds
c.
20 seconds
d.
550 seconds

300 ft at 4 ft /s 
= 300/4= 75 seconds 
then he walked 250ft at 5ft/s 
= 250/5
= 50 seconds 
in total he walked 75+50 = 125 seconds
Therefore the answer is B) 125 seconds 

Distributive property