<PRE><B>Question 355074</B>
you have 3 unknowns, so you need to set up 3 seperate equations;
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let A=number of Adult tickets sold
let C=numer of children tickets sold
let S=numbe of senior tickets sold
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equation 1 (number of tickets):  A+C+S=222
equation 2 (revenues):  7A+5C+4S=1383
equation 3 (relationship):   2A=S+C
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so now you have 3 equations in 3 unknowns</PRE>