


Description 



Substitute: To replace one element of a mathematical equation or expression with another. 
If we have the two equations 2x + y = 8 and y = 4, we can take the fact that 4 can be "substituted" for the y in the first equation so that we are left with 2x + 4 = 8. After doing a little manipulation on the first equation, we find that x must be 2.


