statements
1. ab ≈ ac ~ given
2. abc is isosceles ~ definition of isosceles
3. bd≈cd ~ given
4. angle b ≈ angle c~ base angles an
isosceles triangle are ≈
5. abd2 ≈ acd ~

choose the missing reason in the proof

At the "no mutants allowed" country farm, every sheep has 4 legs, every chicken has two legs, and all animals have only 1 head. asked to count how many sheep and chicken are in the fields, a farm boy reports back that there are 140 feet and 50 heads. how many sheep and chicken are there? there are sheep and chicken at the farm.