Roz has a total $1600 each month. All you need to do is to multiply each percentage to the money she has.
Rent = $1600 (.30) = $480
Food = $1600 (.20) = $320
Utilities = $1600 (.10) = $160
entertainment, clothes, transportation, savings and charity = $1600 [1 – (.3 + .2 + .1)] = $640