The question relates to the total number of pairs of feet ducks and a pigs
are known to have.
Reasons:
The length of the group of ducks and pigs = 40 feet
Number of ducks = Twice the number of pigs
Let x represent the number of pigs, and let y represent the number of ducks, we have;
y = 2 × x
4·x + 2·y = 40
Which gives;
4·x + 2 × (2·x) = 40
8·x = 40
x = 40 ÷ 8 = 5
y = 2 × x
Therefore;
y = 2 × 5 = 10
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