Question

Roberto and Maria Santanos spend approximately $11.50 per week to wash and dry their family's clothes at a local coin laundry. A new washer and dryer would cost them a total of $782. How many weeks will it take for the laundromat cost to equal the cost of a new washer and dryer? ​

Answer 1

68 weeks

Explanation:

1 week costs $11.50.

so, how many such weekly each cycles fit into the price of new machines ?

if they wait to long (to many weeks) they spend in total more money than buying a new machine.

but if they stay still below that max. number of weeks, they have at least the illusion that they are cheaper of with the weekly laundromat investment (but they forget, sooner or later they will need the new machines).

so the break even point is simply

782 / 11.5 = 68 weeks.

after 68 weeks it has cost them exactly the same amount of money, as if they had bought new machines right away at the beginning.