A student test the emission spectra of various known substance and an unknown substance which statement is a qualitative observation of the test

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

if you add everything up correctly you should get 69 i got this because 50 plus 19 is it