Sodium-24 has a half-life of 15 hours.
How many grams of a 900g sample will remain after 90 hours

A. 7.03125g
B. 7.5g
C. 14.0625g
D. 28.125g

(The 24 in Sodium-24 has nothing to do with the equation, that’s just the name.) Please help!! I will give brainliest!! : )