On a farm there are horses and chickens There are total of 4

On a farm there are horses and chickens. There are total of 40 heads and 146 legs. How many horses are on the farm?\" the horses have 3 legs that is all I got I cant help my kid he has this on a test I need to be able to show him how to solve it the numbes can change but they always have 3 legs

Solution

If horses have only three legs you get the following.
If there are \"h\" horses the number of heads is h; the number of legs is 3h.
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If there are \"c\" chickens the number of heads is c; the number of legs is 2c.
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Equations:
Heads: h + c = 40
Legs::3h + 2c = 146
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Solve the 1st equation for \"h\":
h = 40-c
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Substitute that into the Legs equation and solve for \"c\":
3(40-c)+2c = 146
120-3c + 2c = 146
-c = 26
c = -26 (# of chickens is -26)
I guess that makes as much sense as saying the horses have 3 legs.
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Since h = 40-c, h = 40--26 = 66 (# of horses is 66)