The answer is 5,191 reams of paper.
Let's deal with what you know first:
Computer depot sold 762 reams of paper.
Paper palace sold 3 times as much paper as Computer Depot:
This means that we multiply the 762 reams of Computer Depot by 3 to get how much Paper Palace sold:
3 x 762 = 2,286
Paper Palace sold 143 more than Office Supply Central:
So to get this, we know that Office Supply Central sold 143 LESS than Paper palace. Just get the number of reams sold by Paper Palace and subtract 143.
2,286 - 143 = 2,143
Now the main question is how many did all three sell. We just add up all the reams we already solved for:
762 + 2,286 + 2,143 = 5,191
The answer is then 5,191 reams of paper were sold by all three.
762 reams by Computer Depot
2,286 reams by Paper Palace
2,143 reams by Office Supply Central
