Each yogurt is topped with 8 banana slices.  One banana will yield 10 slices.  If Vivian needs to make 5 yogurts, how many bananas does she need to buy?
To make the yogurts, Vivian needs 5 x 8 = <<5*8=40>>40 banana slices.
She needs to buy 40 / 10 = <<40/10=4>>4 bananas.
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