Answer:he eighth sweater costs $29
Explanation:
Let the price of the eighth sweater be re[presented as X
We know that
Mean Price =Total sum of cost of sweater bought/ Number of sweater'
Plugging in our known values we have that
40=$50+ $55+ $30+ $35+ $39+ $40 + $42+X /8
8 X 40 =291 +X
320=291 +X
X =320-291
X=29
Therefore, the eighth sweater costs $29