
_{ }
LESSON 4 : PROBLEM SOLVING USING SYSTEMS OF EQUATIONS
Systems of equations are
often used to solve problems in math, science and business. First we must build a mathematical model
of the problem. The following example illustrates how this
is done. It is followed by a blue box
outlining the key steps in the strategy.
Direction 
Distance 
Speed 
Time 
Equation(d=st) 
upsteam 




downstream 





Distance 
Speed 
Equation(t=d/s) 
At 50 mph 



At 60 mph 


