We have two responses for you
I can get you started on this problem. The technique I am going to use is to work backwards. I'm going to keep track with a table.
The last step was to give 2/7 of the coins that were left to your father leaving you with 25 coins. Since at that stage you gave away 2/7 of your coins then you kept 1 - 2/7 = 5/7 of the coins. Hence 5/7 of the coins is 25 coins. If 5/7 of your coins is 25 coins then 1/7 is 5 coins and 7/7 is 35 coins. Hence before giving coins to your father you had 35 coins.
How many coins did you have before you gave 1/2 to your brother?
Rewrite each of the gifts in terms of what was kept: "I gave some to my mother, keeping 7/8. Then I gave some of what I had then to my brother, keeping 1/2. Then..."
So if the four quantities are A [original] B [after the first gift], C, and D, you have
B = 7/8 A, C = ??? x B, and so on.
You should be able to combine these to get D as a fraction times A. But you know D = 25.
Another way to do this problem is to work through it backwards.
[a: I have ____________coins]
So how many at time [b]? Fill it in below.
I have a bag of gold coins. [c]
So how many at [c]?
Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.