Billy ate 20 apples this week. On Monday, he ate 2 apples. On Tuesday, he ate twice as many as he ate the day before. He’s not sure what he ate on Wednesday. On Thursday, he ate four times as many as he ate on Friday. On Friday, he ate half of the amount he ate on Monday.  How many apples did he eat on Wednesday?
How many apples did Billy eat on Tuesday? ** On Tuesday, Billy ate 2 * 2 = <<2*2=4>>4 apples.
How many apples did Billy eat on Friday? ** On Friday, he ate 2 * 0.5 = <<2*0.5=1>>1 apple.
How many apples did Billy eat on Thursday? ** On Thursday, he ate 4 * 1 = <<4*1=4>>4 apples.
How many apples did Billy eat in total? ** So for Monday, Tuesday, Thursday, and Friday, Billy ate a total of 2 + 4 + 4 + 1 = <<2+4+4+1=11>>11 apples.
How many apples did Billy eat on Wednesday? ** This means that on Wednesday, he must have eaten 20 – 11 = <<20-11=9>>9 apples.
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