A farm has cows and chickens with 30 heads and 74 legs. How many cows are there?
Hint: Pretend they're all chickens first.
7 cows.
30 chickens would have 60 legs. The extra 14 legs come from cows, which have 2 more legs each, so 14 ÷ 2 = 7 cows (and 23 chickens).
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