312 greeting cards in 24-card boxes require 13 boxes.
312/24=13
We want to isolate T. So, we will divided IR from both sides, so our equation is now
P/IR=T
There ya go!
To solve for the given problem above:
Let x be the number of boxes left after 3 hours
3 * ½ X = 24
3/2 X = 24
X = 24 * 2/3
X = 16
The correct answer is 16.