If principal = 4,500 pesos, rate 1. 25% and time 5 years find the simple interest.

1millimetre (mm)= 0.001 meter
1 centimeter (cm)= 0.01 meter
1 kilometre (km)= 1,000 meters

Let 
v = velocity of the water, and 
k = kent's normal swimming speed. 

upstream he swam at speed k-v, and downstream he swam at speed k+v. 

(k-v)*5min = 150m 
(k+v)*3min = 150m 
k-v = 30 meters/min 
k+v = 50 meters/min 

thus 
k = 40 meters/min 
v = 10 meters/min 

so he would have swum 40 meters/min in still water, and the speed of the water is 10 meters/min.

Well you can also save and spend money with a bank account

The answer is a+b/ im not !