First find how many inches the hem is by multiplying the length in feet by the number of inches per foot: 3 feet * 12 inches/foot = <<3*12=36>>36 inches
Then divide the length in inches by the length of each stitch to find how many stitches Jenna makes: 36 inches / .25 inches = <<36/.25=144>>144 stitches
Then divide the number of stitches by Jenna's stitching rate to find how long it takes her: 144 stitches / 24 stitches/minute = <<144/24=6>>6 minutes
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