Equal angles are usually called ''alternate angles''.
C=chicken
p=pigs
c+p=13~p=13-c (plug in)
2c+4p=40
2c+4(13-c)=40
2c+52-4c=40
-2c=-12
c=6
6+p=13
p=7
6 chickens
7 pigs
Well first, you have to know the distance formula. You plug the coordinates into it and you get the answer.

√1² + -7² = d
d = 7.1
Step-by-step explanation:
There isn't any equation given, so there isn't anything to do here