Let a be the amt of perfume A, and b be the amt of perfume B. We have been given that
a+b=3 and that a∗15+b∗35=63
From equation 1, we substitute b=3−a so as to get, a∗15+(3−a)∗35=63
which means, 15a+105−35a=63 which means, −20a=−42
so a = 2.1 ounce and b = 0.9 ounce