<PRE><B>Question 655930</B>
A pet store owner spent $100 to buy 100 animals.
 He bought at Least one iguana , one guinea pig, and one mouse,
 But no other kind of animals.
 if an iguana cost $10 a guinea pig cost $3, and a mouse cost $.50.
 how many of each did he buy?
:
let i = no. of iquanas
let p = no. of g pigs
let m = no. of mice
:
we got three unknowns and 2 equations here, will have to use some logic here
:
The cost equation
10i + 3p + .5m = 100
and no. of creatures equation
i + p + m = 100
:
Multiply the first equation by 2, subtract the above equation
20i + 6p + 1m = 200
1i + 1p + 1m = 100
---------------------
19i + 5p = 100
5p = -19i + 100
divide by 5
p = {{{-19/5}}}i + 20
the only integer solution here is i = 5 iquanas, then
p = -19 + 20
p = 1 pig
:
m = 100 - 5 - 1
m = 94 mice
:
see if that work out
10(5) + 1(3) + 94(.5) = 
50 + 3 + 47 = 100
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