1) Cement Mortar is being prepared by mixing cement to sand in the ratio of 1:6 by volume. In a cement mortar of 42 units of volume , how much more cement needs to be added to enrich the mortar to the ratio 2:9?

2) In a solution of common salt in water, the ratio of salt to water was 30:70 as per weight. If we evaporate 100gms of water from one kg of this solution, what will be the ratio of the salt to water by weight?

Since this is obviously homework.. and we don't do your assignment for you per the site rules I'm sure you read...

SHow the answer you got... and the work for how you got there... then we can discuss what you might have done wrong.