After mom gave each girl an equal amount of money for this months allowance, lily had twice as much money as Elsa. Thus mom gave $ 320 to each girl
<em><u>Solution:</u></em>
Given that Lily and Elsa are both college students
Before mom gave them this months allowance lily had $750 and Elsa had &215
<em><u>Amount (in dollars) with Lily and Elsa already is given as:</u></em>
amount with Lily = $ 750
amount with Elsa = $ 215
After mom gave each girl an equal amount of money for this months allowance, lily had twice as much money as Elsa
Let "x" be the equal amount of money which mom gave to Lily and Elsa
Now amount with Lily and Elsa after mom gave equal amount is:
amount with Lily = amount with Lily already + x
amount with Lily = 750 + x
amount with Elsa = amount with Elsa already + x
amount with Elsa = 215 + x
Given that lily had twice as much money as Elsa
Amount with lily = 2(amount with elsa)
750 + x = 2(215 + x)
750 + x = 430 + 2ax
2x - x = 750 - 430
x = 320
Therefore mom gave $ 320 to each girl
