systems of equations

Question

Martha saw parrots and deer in a park. she counted 45 heads and 140 legs. how many parrots were there?

Answer 1

Martha has a lot of free time on her hands. If she can count heads & legs, why can't she count parrots & deer. Hard to believe they'd stay still long enough to count anything. Unless they're stuffed animals.

But, be that as it may, the number of parrot heads + deer heads = 45. P+D =45. D=45-P

parrot legs plus deer legs = 140. 2P +4D =140. 2P + 4(45-P)= 140.

Assuming all deer have 4 legs and all parrots have 2 legs. No one legged parrots or 3 legged deer allowed.

2P + 180 -4P = 140

2P = 40

P = 20 parrots

D = 25 deer

25 deer have 100 legs. 20 parrots have 40 legs. Grand total 140

parrots' heads plus deer heads = 20 + 25 = 45