Question 829840
One could change the variable names like this and use, as you have chosen, to use decimal fractions instead of percents:


C = 0.93 for the stock concentration
T = 0.03 for the Target concentration
u = ml. volume of the stock solution to add or use
V = 1000 ml. volume of your target, desired solution


Amount of solute from stock will be the amount of solute of your desired solution.  Your initial idea was correct, and using the variable names chosen in this posting, you would write:

{{{C*u=T*V}}}
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Solve for u.
{{{Cu/C=TV/C}}}
{{{u=TV/C}}}
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You wanted a known V, volume of the finished solution, 1000 ml.  You are adding the quantity u to some amount of solvent (probably water, but it would be whatever solvent you are using).  
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What is u?
{{{u=0.03(1000)/(0.93)}}}
{{{highlight(u=32)}}} mililiters
THAT u is what quantity you add to water,  and the amount of water, avoiding further variable usage, is {{{1000-32=968}}} ml. or the quantity enough to make up to your 1000 ml. of solution.