Answer:
$28.
Step-by-step explanation:
Let y represent of saved money and x represent amount of earned money.
We have been given that the amount of money that Charlie saves each week is directly proportional to the amount he earns.
We know that two proportional quantities are in form
, where, k is constant of proportionality.
Substitute given values and solve for k:



To find amount of saved money, we will substitute
and
in our equation.


Therefore, Charlie saved $28 in the given week.