Answer:
140 are in the warehouse.
Step-by-step explanation:
In 3 1/2 hours (3:30 pm) the number of boxes that had been unloaded was the total - 55
The total is 90 so at 3:30 the number unloaded was 90 - 55 = 35
At 8:30 we are finally done, so set up a proportion.
3 1/2 / 35 = 8 1/2 / x Cross Multiply
3.5x = 8.5*35 Combine
3.5x = 297.5 Divide by 3.5
x = 297.5 / 3.5
x = 85
That empties the truck but it does not tell is what's in the warehouse.
There are 55 more boxes that were there to start with
85+ 55 = 140
