A 10 g sample of tritium decays to 8.5 grams in 2.93 years. What is the half life of tritium

the formula is y= A (0.5)^t/h

so A is the original amound, t is the time, and h is the half life, y is the changed amount...

i tried doing it but i didnt know...can anybody help? Does it involve logarithms?

this is what i got:

8.5 = 10 (0.5) ^2.93/h

log 8.5 = log (10/2) ^ 2.93/h

h = 2.93 log 8.5 / log 10/2