Need help geometry question central angles and arcs pls???

What is the difference between the equations of a vertical and a horizontal line?

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

Complete the equation of the live through (-1,6) (7,-2)