Wilson had $150 + $17= $<<150+17=167>>167 two months ago before making a withdrawal.
His money in his account now is $150 + $16 = $<<150+16=166>>166.
Since he deposited $21 this month, this means there was $166 - $21 = $145 last month after making a withdrawal.
Therefore, Wilson withdrew $167 - $145 = $<<167-145=22>>22.
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