If y varies inversely as x and y=3 when x=4 then y=12 when x=15 true or false

In the first case, x*y = 4*3 = 12
In the second case, x*y = 15*12 = 180

The results 12 and 180 don't match, so the answer is false

Side Note: if x and y vary inversely with one another, then x*y = k for some fixed number k

Line the mark up so you will find your answer