Question 394291
Let I = income
Let {{{g}}} = number of glasses sold
Let {{{x}}} = number to subtract from glasses sold
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For 1st situation:
{{{I = 125g}}} (in cents)
{{{g = 30}}}
{{{I = 3750}}}
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For 2nd situation:
{{{I = (125 + 10x)*(30 - x)}}} (in cents)
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You need a chart that shows {{{I}}} and {{{x}}} for
{{{x}}} = 1,2,3,... etc. Then compare {{{I}}} with 
{{{I = 3750}}} in the 1st situation.
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For instance:
{{{x = 1}}}
{{{I = (125 + 10)*(30 - 1)}}}
{{{I = 135*29}}}
{{{I = 3915}}} The income went up
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Just keep computing