Question

In a zoo, there are some pigeons and some rabbits. If their heads are counted these are 100 and if their le.G.S are counted these are 320. How many pigeons are there?

Answer 1

let number of pegions be x and number of rabbits be y

both pegions and rabbits have only one head
.:ACCORDING TO CONDITION I
x+y=100. ......(1)

pegions have 2 legs and rabbits 4
.:ACCORDING TO CONDITION II
2x+4y=320. .....(2)

Multiply equation (1) by 2 we get
2x+2y=200. ......(3)

Subtracting equation (3) from(2)
.: 2x+4y-(2x+2y)=320-200
.: 2x+4y-2x-2y= 120. ....(opening the bracket)
.:2y=120
.:y=60

Substituting y=60 in equation (1)
x+y=100. .....(equation 1)
.:x+60=100
.:x=100-60
.:x=40

ANSWER
there are 40 pegions and 60 rabbits in the zoo