Answer: $111.11
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Step-by-step explanation:
Let's say you earn x dollars.
You pay 10% tax on that, which means you pay 0.10x dollars.
This would drop to x-0.10x = 0.90x which is the amount earned after tax.
So you pay 10% of what you earn, and keep 90% of the rest.
Set this equal to the target $100 you want and solve for x.
0.90x = 100
x = 100/0.90
x = 111.11
Notice that 10% of this is 0.10*x = 0.10*111.11 = 1.11 when rounding to the nearest penny. So you'll pay $1.11 in tax. Therefore, you'd have x-0.10x = 111.11 - 1.11 = 100 left over. So the answer checks out.