Question 490209
your equation is:


profit = .15 times the number of e-readers sold minus 28


sounds like you have a fixed cost of 28 that needs to be taken care of before you can get a profit.


let x equal the number of e-readers sold.


your equation becomes:


profit = .15 * x - 28


if profit is negative then you've taken a loss.
if profit is positive then you've taken a profit.
if profit is equal to 0 then you've broken even.


to find out what the break even point is, set profit equal to 0 and solve for x.


you get:


0 = .15 * x - 28
add 28 to both sides of the equation to get .15x = 28
divide both sides of the equation by .15 to get x = 28/.15 which becomes:
x = 186.66666667


you need to sell at least 187 e-readers to make a profit.
if you sell 186 e-readers you take a loss.
you will break even if  you sell 186.66666667 e-readers.
since this is impossible, you will never break exactly even but you will get close.


assume the number of e-readers sold is 186.
your profit is .15*186 - 28 = -.l


assume the number of e-readers sold is 187.
your profit is .15*187 - 28 = .05


assume the number of e-readers sold is 186.666666667, ignoring the fact that you can't sell a partial number of e-readers.
your profit is .15 * 186.6666667 - 28 = 0
any difference from 0 is due to rounding error since 186.6666667 is really 186.666666666666666666666666666666 all the way to infinity.
the exact number is 186 and 2/3 which you can use in the calculation in place of the decimal equivalent.
you get profit = .15 * (186 + 2/3) - 28 which becomes:
profit = .15 * 186 + .15 * 2/3 - 28 which becomes:
profit = 27.9 + .1 - 28 which becomes 28 - 28 which becomes 0.


if the values are given in 1000, this means that we would have to multiply the answer by 1000 to get the real numbers.


assume that 500 e-readers were sold.


profit would be equal to .15 * 500 - 28 which results in:
profit = 47


since we're really dealing in thousands, then 28 represents 28,000 and 500 represents 500,000 and the equation then becomes:


profit = .15 * 500,000 - 28,000 which resuls in:
profit = 47,000


that's my interpretation of the statement "values given in 1000"


that, of course, is open to interpretation, and you need to verify that's what is meant before assuming the conversion i just told you is correct.