I am brain dead right now? plz help

What is the y intercept of f(x)=(1/2)^x?

Katie wants to collect over 100 seashells. she already has 34 seashells in her collection. each day, she finds 12 more seashells on the beach. katie can use fractions of days to find seashells. write an inequality to determine the number of days, dd, it will take katie to collect over 100 seashells.

Yvaries directly as x. y =90 when x=6. find y when x=13