Me i stink at this

noemi wrote this expression to describe the number of homework problems she has left to do.

30 – h

which situation could be described by this expression?

a.
noemi knows she has 30 homework problems. she does not know how many she has completed.

b.
noemi knows she has completed 30 homework problems. she does not know how many she has left.

c.
noemi knows she has completed 30 homework problems. she doesn't know how many she was assigned.

d.
noemi knows she has 30 homework problems. she knows she has twice as many left.