- Thread starter MT Schull
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Do you know algebra?MT Schull said:Kevin has pheasants and rabbits. He has a total of 42 heads and 138 legs. How many pheasants and rabbits does kevin have?

If you don't - then of course you cannot do the way Denis suggested.

In case you don't know algebra - then it is an "educated" guessing method.

Start with equal number of pheasants and rabbits - 21 each.

Now you have 126 legs and 42 heads.

You are short of legs - 12 legs. To increase the number of legs - you need to exchange 1 pheasant for 1 rabbit. For increasing the no of rabbit by one (and decreasing number of pheasants) - you will gain 2 legs.

You need to increase 12 legs - so how many pheasants must you exchange (for rabbits)?

Is this correct?

P=42-r

2(42-r)+4r=138

84-2r+4r=138

84+2r=138

2r=138-84

2r=54

r=27

2p+4(27)=138

2p+108=138

2p=138-108

2p=30

p=15

Kevin at 15 pheasants and 27 rabbits

15pheasant x2 legs=30 legs

27rabbitsx4 legs=108 legs

30+108=138

Thanks for the nudge. MT Schull

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MT Schull said:2p + 4r = 138

p = 42 - r

Is this correct? Yes

Include definitions for symbols p and r, when you turn in your work.

I see that you checked your solution. That's smart.

r = 27

2p + 4(27) = 138

Instead of going back to this equation, to determine p, here's another approach.

You already wrote a formula for p in terms of r (above). Now that you know r = 27, you can use that formula.

p = 42 - r

p = 42 - 27