Question 1141747
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    4d + 2p = 84     (1)     (counting legs)

     d -  p =  3     (2)     (counting heads)


where "d" is the number of dogs and "p" is the number of people.


From eq(2) express p = d - 3  and substitute it into eq(1). You will get


    4d + 2*(d-3) = 84

    6d - 6 = 84

    6d = 84 + 6 = 90

    d = 90/6 = 15.


<U>ANSWER</U>.  15 dogs.
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