story problem!!! help please midterm study.

Select the equation that represents this situation.
A merchant has eight crates, each with the same number of hammers.
However, the number of hammers in each crate is unknown.
The merchant sells 20 hammers from the first four boxes.
He then sells four complete, unopened crates of hammers and is left
with 120 hammers total.
A) 8x – 20 -4x = 120
B) 4x – 20 + 8x = 120
C) 8x + 4x = 120 – 20
D) 8x – 120 – 4x = 20