adkikani wrote:
After taxes, Sally takes home a salary of J = $5000 every month. She pays P percent of this to her rent and all her fixed bills each month, leaving her with K left. She spends half of K on groceries, leaving her with L left. If she spends \(\frac{1}{3}\) of L on gifts and puts \(\frac{2}{5}\)
of L into her savings account, this would leave her with $200 for miscellaneous expenses. What is the value of P?
A. 30
B. 40
C. 50
D. 60
E. 70
Instead of solving the problem algebraically, let’s make an educated guess for the value of P. Let’s guess P = 40 and check whether it satisfies all the criteria of the problem.
If P = 40, Sally pays 0.4 x 5000 = $2000 for rent and all her fixed bills, leaving her with 5000 - 2000 = $3000 (i.e., K = 3000). She then spends ½ x 3000 = 1500 on groceries, leaving her with 3000 - 1500 = $1500 (i.e., L = 1500). She then spends ⅓ x 1500 = $500 on gifts and puts ⅖ x 1500 = $600 into her savings account. This would leave her with 1500 - 500 - 600 = $400 for miscellaneous expenses. However, since we are given that she is left with only $200, we see that 40 is not the correct answer.
Let’s try P = 70.
If P = 70, Sally pays 0.7 x 5000 = $3500 for rent and all her fixed bills, leaving her with 5000 - 3500 = $1500 (i.e., K = 1500). She then spends ½ x 1500 = 750 on groceries, leaving her with 1500 - 750 = $750 (i.e., L = 750). She then spends ⅓ x 750 = $250 on gifts and puts ⅖ x 750 = $300 into her savings account. This would leave her with 750 - 250 - 300 = $200 for miscellaneous expenses. Since this matches the dollar amount of her miscellaneous expenses, we see that P = 70.
(Note: The reason we try 40 and 70 first is because of the dollar amount for K. Notice that K would be 3000 and 1500, respectively, which are numbers for which we can easily take ½, ⅓ and ⅖ of. Had we used P = 50, we see that K would have been 2500, which is not easily divided by 3.)
Answer: E