There are two different compounds of sulfur and fluorine. in sf6, the mass of fluorine per gram of sulfur is 3.55 g f/g s. in the other compound, sfx, the mass of fluorine per gram of sulfur is 1.18 g f/g s. what is the value of x for the second compound

For the answer to the question above, 1.18 x 3 = 3.55.
First, you need to find the ratio of F to F in each compound. It is the law of multiple proportions stating that the masses of one element which combine with a fixed mass of the second element are in a ratio of whole numbers. In this case, F would be the "one element" and S would be the "fixed mass", the ratio of F6 to Fx = 3:1 
therefore x would be 2 since there is less F in SFx and the ratio is 3:1. divide 6 by 3 and you get 2.

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.