A shopkeeper earns a profit of $1 by selling one pen and incurs a loss of 40 cents per pencil while selling pencils of her old stock.
a)In a particular month she incurs a loss of $5. In this period, she sold 45 pens. How many pencils did she sell in this period?
b)In the next month she earns neither profit nor loss. If she sold 70 pens, how many pencils did she sell?
a) She sold 45 pens, so she made $45 in profit from the pens. But she lost a total of $50 to end up with a net $5 loss. So she must have sold ($50/$0.4 per pencil) = 125 pencils.
b) She sold 70 pens, so she made $70 selling pens. But she lost $70 selling pencils in order to break even, so she sold ($70/$0.4 per pencil) = 175 pencils.
(She needs to stop selling pencils…)
a) 45 pens = $45
45-50 = -$5
50 / 0.40 = 125
125 pencils.
b) 70 pens = $70
70-70 = $0
70 / 0.40 = 175
175 pencils.