# Math Help - precentages

1. ## precentages

if i sell cd's for $28 each. and i have an option to work for either straight commission of 15% or 8% and a retainer of 150 a week. how many cd's do i need to sell in a week to be better off on a straight commission plz show working out 2. Originally Posted by n7x if i sell cd's for$28 each. and i have an option to work for either straight commission of 15% or 8% and a retainer of 150 a week. how many cd's do i need to sell in a week to be better off on a straight commission

plz show working out
Your salary if you work for the 15% commission and selling x CD's is

$S_{15}=.15(28)x=4.2x$

$S_{8}=150+.08(28)x=150+2.24x$

We want to know when

$S_{15} \ge S_{8} \iff 4.2x \ge 150+2.24x \iff 1.96x \ge 150 \iff x \ge 76.53$

You will make more money if you sell more than 77 CD's per month.

3. LOL well done. well done. now i need this to look like a year 11 kid did it haha?

4. Originally Posted by n7x
if i sell cd's for \$28 each. and i have an option to work for either straight commission of 15% or 8% and a retainer of 150 a week. how many cd's do i need to sell in a week to be better off on a straight commission

plz show working out
Let x denote the number of sold CD's.

1. Your income by straight commission: $I_1=x \cdot 28 \cdot 15\% = x \cdot 28 \cdot \frac{15}{100}$

2. Your income by retainer and reduced commision: $I_2= x \cdot 28 \cdot 8\% + 150 = x \cdot 28 \cdot \frac8{100} + 150$

3. Calculate for which value of x both incomes are equal. I've got: $x \geq 77$ will yield a higher income $I_1$

EDIT: Too fast for me, TES