Help me on this and where do I put the dots?

Seth practice piano for 1 1/3 hours on saturday and 5/6 hour on sunday for much longer did he practice on saturday than on sunday?

(a) calculate the molarity of a solution that contains 0.0345 mol nh4cl in 400 ml of solution. (b) how many moles of hno3 are present in 35.0 ml of a 2.20 m solution of nitric acid? (c) how many milliliters of 1.50 m koh solution are needed to supply 0.125 mil of koh ?

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.