Water is added to 54.0 mL of a 1.70 M solution to give a volume of 248 mL. 124 mL is taken from that solution and 177 mL of water is added. Calculate the concentration of this final solution.
1.70 M solution x (54.0 mL/248 mL) = ? M which I will call Y.
Then Y M solution x [124/(124+177)] = ? M
OR you could use the dilution formula twice; e.g..
mLa x Ma = mLb x Mb
1.70M x 54.0 mL = 248 mL x Mb and solve for M base which is Y M
Then YM x 124 mL = (177 mL + 124 mL) x Mb and solve for Mb