question: Chris is way behind on his math homework. He has 100 math problems to complete in total. He completes 12 problems on Monday night. On Tuesday, he completes 3 times as many problems as he did on Monday. On Wednesday, he completes one-quarter of the remaining math problems. How many math problems does he have left to complete on Thursday?
answer: On Tuesday he completes 3 * 12 = <<3*12=36>>36 math problems.
  This leaves him with 100 - 12 - 36 = <<100-12-36=52>>52 math problems to complete.
  On Wednesday he completes 52 * 0.25 = <<52*0.25=13>>13 math problems.
  This leaves him with 52 - 13 = <<52-13=39>>39 math problems to complete on Thursday.
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