Seventy-five percent (75%) by mass of the imaginary compound XY is made up of X. Knowing this, what is the percent by mass of element X in the imaginary compound XY2

i'm assuming that the correct answer is indeed the first one/ "a"..

i think the answer is terrae but not 100 percent sure. ▓▬▬ §

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer