Call the number of pizzas x;They buy pizzas from the supplier at:4x+100They sell at:7xWhen these two expressions match they will start to make a profit; so:4x+100=7xRearranging:3x=100x=1003=33.3So after the 33rd pizza they will start to make a profit.For example at the 34th they have payed:34%C3%974+100=236$ to the supplier;Selling they will get: 7%C3%9734=238$. sorry if this is complex
