need algebra help on how to solve two different problems

Evaluate the given expression if y = 2/5 and z = 5/612y-z=?Also Simplify the complex fraction of23k/12 divide 11/6 =?I have not done these type of prblems yet and am uncertain on how to work and solve these as well. can you also help me with these?I would greatly appreciate any and all help. Thanking you in advance.