So there would be two equations
120=x+y
and
4850=45x+35y
We can now solve for each variable
y=120-x
plug it into the second equation...
4850=45x+35(120-x)
4850=45x+4200-35x
650=10x
x=65
Now plug in X
y=120-65
y=55
They are carrying 65 big boxes and 55 small boxes.
Check
---------
120=y+x
120=55+65
120=120
Brainliest/Heart would help!