At one point in the contest, the jar contains 4 slips for a 5% discount, y slips for an x% discount, and 2 slips for a 15% discount. if the expected value on the next draw is 8%, the value of y is
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We are given a scenario at which a jar contains the following slips for a raffle draw:

4 slips for a 5 percent discount. 
y slips for an x percent discount
2 slips for a 15 percent  discount

if the expected value on the next draw is 8 percent, the value of y can be determined by assuming that the 8% is the value of x.
 
If x = 8 percent  then we can solve for the value of y by ratio and proportion:

4 / 0.05 = y/ 0.08

then y is approximately equal to 6 slips.