Let
x -----> the number of cows
y -----> the number of chickens
we know that
x+y=100 --------> equation A
4x+2y=286 ------> equation B
Remember that, a cow has 4 legs and a chicken has two legs
solve the system of equations
Using a graphing tool
solve the system of equation by graphing
The solution is the intersection point both graphs
see the attached figure
the solution is the point (43,57)
therefore