If the price has fallen by 10% what percent of its consumption be: increased so that the expenditure may be the same as before?

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If the price has fallen by 10% what percent of its consumption be: increased so that the expenditure may be the same as before?

A. 11%
B. 10%
C. 11 1/9 %
D. 9 1/11 %
100 – 10 = 90
90——10
100——? => 11 1/9%