What is the sum of all positive integers n for which lcm(10, 18, n) = 630 and gcd(10, 18, n) = 2? i really need the explanation and the rule for how to do these types of problems.

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of