What is the greatest common factor of 42 and 50

Find the zero function by factoring (try to show work) h(x)=-x^2-6x-9

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.

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