I will answer your question...
In box A there were (at first) 250 balls and
in box B were (at first) 40 balls (\(250+40\)).
I suggested you to get trys and then get an answer,
but if you're trying please note that the balls on
each side must be divided by 5.
Use for example:
in-box A | in-box B |
270 balls | 20 balls |
162 balls | 128 balls |
(\(162-128=34\))
in-box A | in-box B |
260 balls | 30 balls |
156 balls | 134 balls |
(\(156-134=22\))
You see the differences beetween the first and the second chart they're only (\(34-22=\)) (\(12\)).
And the differences are ALWAYS 12, so (\(22-12=10\)) and 10 is the difference we should get.
I subtract now 260 balls to 250 balls (like I did) and add these 10 to the 30 balls (\(260-10=250, 30+10=40\))
I know that we are getting the difference of 10, but still I make a chart for a proof:
in-box A | in-box B |
250 balls | 40 balls |
150 balls | 140 balls |
The difference is now (\(150-140=\)) 10 and that is what we should get.
Straight