Question 114485
‘n’ litres of oil was poured into a tank and it was still e% empty. How much oil must be poured into the tank in order to fill it to the brim. 
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The n litres occupies (100-e)% of the tank.
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Proportion:
Let x litres be the capacity of the tank
n/(100-e)% = x/100%
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x = n/(100-e)%
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The tank already has n litres in it.
You need [n/(100-e)%]-n = [100n/(100-e)]-n 
= [100n-n(100-e)]/(100-e) 
= ne/(100-e) litres to fill the tank
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Cheers,
Stan H.
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