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