SOLUTION: Lisa keeps ants and spiders as pets. She counted the legs and heads of these pets and found that there were 126 legs and 19 heads. How many ants were there?

Question 1091149: Lisa keeps ants and spiders as pets. She counted the legs and heads of these pets and found that there were 126 legs and 19 heads. How many ants were there?
Answer by ikleyn(52887) (Show Source): You can put this solution on YOUR website!
.
Ants have 6 legs (Wikipedia, https://en.wikipedia.org/wiki/Ant).

      It is amaizing: there are 22000 estimated species, of them 15000 classified,  

      and ALL have 6 legs (!)

Spiders have 8 legs (Wikipedia, https://en.wikipedia.org/wiki/Spider).

Equations:

 A +  S =  19,       (1)   heads,   and
6A + 8S = 126        (2)   legs.


Multiply (1) by 6 (both sides). You will get

6A + 6S = 114,       (1')
6A + 8S = 126.


Now subtract (1') from (2') (both sides). You will get

2S = 126 - 114 = 12  ====>  S =  = 6.


Answer.  6 spiders and 19-6 = 13 ants.


Check.   13*6 + 6*8 = 126.   ! Correct !

Solved.

RELATED QUESTIONS
In Aunt Melly�s attics there are also spiders and ants, the total of 136 legs and 20... (answered by Boreal)

In Aunt Peggy�s attics there are spiders and ants, the total of 160 legs. And, there is... (answered by Alan3354)

In Aunt Peggy�s attics there are spiders and ants, the total of 160 legs. And, there is... (answered by Boreal)

A boy had a box containing a total of 8 spiders and beetles. He counted 54 legs... (answered by Edwin McCravy)

Mr.sparrow was terrified when he opened his door and saw 88 legs scurrying across the... (answered by fractalier)

Martians have two heads and five legs. There was a "meet and greet" party that had both... (answered by josmiceli,Theo,LinnW)

If a farmer did head count and got 200 livestock (and he keeps chicken n pigs), counted... (answered by fcabanski)

A farmer had some chickens and some cows. She counted 40 heads and 126 legs. How many... (answered by rfer)

While on a safari in Africa I saw a small herd of zebras and cranes wandering over the... (answered by unlockmath)