SOLUTION: if i have 8 creatures and some have 4 legs and others have 6 legs and all the legs add up to 36. how many of each kind of creature can i have? solving two ways

Solving it in your head without algebra:

Consider all 8 creatures as having 4-legs, and some creatures have 
1 extra pair of legs.  So 8×4 = 32 legs are accounted for.  The 
extra 4 legs means that two of the 8 creatures have an extra pair 
of legs. So, 6 of the 8 have only 4 legs and the other two have an 
extra pair, or six legs. 

Solving by algebra:

Let x = the number of 4-legged creatures
Let y = the number of 6 legges creatures

 x +  y =  8
4x + 6y = 36

Solve the system and get x = 6 and y = 2

Edwin