There are crows and groundhogs in a field. All of them together have 15 heads and 40 legs. How many of each animal are in the field?
+781 Let x be the number of crows and 15-x the number of groundhogs. Note that crows have 2 legs and groundhogs 4. We form an equation for the number of legs.
2x+4(15-x)=40
2x+60-4x=40
-2x=-20
x=10
There are 10 crows and 15-10=5 groundhogs.
