
Word problem.. anyone?
Liquid A has 10 grams of element X per liter. Liquid B has 15 milligrams of element Y per cm^3 (there are 1000 milligrams in a gram and 1000 cm^3 in a liter). It is desired to make 130 grams of molecule Z. To make 18 grams of Z requires 2 grams of X and 16 grams of Y. How many liters of each liquid should be used?

I will quickly try to tackle this. (Evilgrin)
We have;
$\displaystyle (1)~~~A~=~10gl^{1}~of~X$
$\displaystyle (2)~~~B~=~15mgcm^{3}~of~Y$
$\displaystyle ~=~15\cdot10^{3}gcm^{3}$
$\displaystyle ~=~15gl^{1}$
$\displaystyle 18g~of~Z~=~2g~of~X~+~16g~of~Y$
$\displaystyle \implies~130g~of~Z~=~\frac{130}{9}g~of~X~+~\frac{1 040}{9}g~of~Y$
We want $\displaystyle \frac{130}{9}g~of~X$ hence we need $\displaystyle \frac{130}{90}l$ of $\displaystyle A$
We also want $\displaystyle \frac{1040}{9}g~of~Y$ hence need $\displaystyle \frac{208}{27}l$ of $\displaystyle B$