Miriam is trying to exercise more and figures if she counts her exercises it will be encouraging to see her numbers go up. On Monday she does 5 push-ups. On Tuesday she does 7 push-ups. On Wednesday she does twice as many push-ups as the day before. On Thursday she does half the number of total pushups she already did that week. Finally, on Friday she does as many pushups as the total number she did over the previous four days. How many pushups does Miriam do on Friday?
On Monday Miriam does 5 push-ups + 7 push-ups on Tuesday = <<5+7=12>>12 push-ups on both days.
On Wednesday she does twice as many push-ups as she did on Tuesday, 7 x 2 = <<7*2=14>>14 push-ups on Wednesday.
Over the first 3 days, she did a total of 14 + 12 = <<14+12=26>>26 pushups
On Thursday Miriam did 1/2 the same number of total pushups she had already done that week, so she did 1/2 x 26 = <<1/2*26=13>>13 pushups on Thursday.
On Friday she does as many push-ups as the total of what she had done over the previous four days, so she did 5 + 7 + 14 + 13 = <<5+7+14+13=39>>39 push-ups on Friday.
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