Question 256010
Let {{{x}}} = number that he must sell
In words:
(cost/orange x oranges sold) - (cost/orange x oranges bought) = profit
{{{(200/5)*x - (100/3)*x = 1000}}}
(in cents)
Multiply both sides by {{{15}}}
{{{600x - 500x = 15000}}}
{{{100x = 15000}}}
{{{x = 150}}}
He must sell 150 oranges
check:
{{{(200/5)*x - (100/3)*x = 1000}}}
{{{(200/5)*150 - (100/3)*150 = 1000}}} 
{{{150*(200/5 - 100/3) = 1000}}}
{{{200/5 - 100/3 = 20/3}}}
Multiply both sides by {{{15}}}
{{{600 - 500 = 100}}}
OK