Word problem

Question

A farmer had some ducks and cows in the field. He sent his children out to count the number of animals. Jean counted 50 heads. Charles counted 154 legs. How many of each kind were counted?

Answer 1

Let D= number of ducks 2 legs per duck

C=number of cows 4 legs per cow

  D+  C=50

2D+4C=154

now solve