Iwant to understand how you do this (not just the answer) and what formula(s) i have to use. 1.00ml of a 3.50x10^-4 m solution of oleic acid is diluted with 9.00ml of petroleum ether, forming solution a. then 2.00ml of solution a is diluted with 8.00ml of petroleum ether, forming solution b. what is the concentration of solution b?

To solve this we use the equation, 

M1V1 = M2V2

where M1 is the concentration of the stock solution, V1 is the volume of the stock solution, M2 is the concentration of the new solution and V2 is its volume.

Consider solution A 
3.5 * 10^–4 * 1 = M2 * (9+1) 
M2 = 3.50x10^(–5) M 
conc of A = 3.50x10^(–5)M 

Consider solution B 
2 * 3.50x10^(–5) = M2 * (8+2) 
M2 = 7*10^(-6) M 
conc of B = 7*10^(-6) M