3 brothers Gerald,Xavier and Joshua shared a box of cookies.Gerald took 45% of the cookies.Xavier took 25% of the cookies taken by Gerald and Joshua.If Gerald took 25 morecookies than Xavier,how many cookies did the box contain at first?
THANKS!

First I would change the percentages to ratios:
A: Gerald took 45%
G : X+J
45 : 55

B: Xavier took 25% of Gerald and Joshua
X : G+J
1 : 4

Next, total cookies is G+X+J. But G+X+J is 100units in A and 5units in B. So make the totals the same by multiplying B by 20
X : G+J
20 : 80

Combining the ratios
G:X:J
45:20:35

Gerald took 25 more cookies than Xavier
--> 45u-20u = 25u
--> 25u = 25
--> u=1

There are a total of 100u --> 100x1
--> 100 cookies