Prepare 150 ml of a reaction buffer containing 0.75% MgCl2, 35mM glucose, 750 nM ATP, and 20 mM Tris-Cl, pH 7.5. In addition, you have a 20% MgCl2 stock solution and the lab freezer has 10 mM ATP that you can dilute to the correct concentration.

The MgCl2 you get by c1v1 = c2v2 where c is concn and v is volume.

glucose you get by mols = grams/molar mass.
ATP is c1v1 = c2v2
tris-cl you get by use the Henderson-Hasselbalch equation in a manner similar to your last post.