Kaden and John had some marbles. John gave away 3/5 as many marbles as Kaden and was left with 4 fewer marbles than the marbles he gave away. Kaden has 2/5 as many marbles left as John. The difference between the number of marbles they had in the end was 21. How many marbles did Kaden have at first?
Call the number of marbles that Kaden gave away = G
Call the number of marbles that John gave away = (3/5)G
The number of marbles that John ends up with = (3/5)G - 4
The number of marbles that Kaden ends up with = (2/5) [ (3/5)G - 4]
So
(3/5)G - 4 - (2/5) [ (3/5)G - 4 ] = 21 simplify
(3/5)G - (6/25)G - 4 + 8/5 = 21
(15/25)G - (6/25)G - 4 + 8/5 = 21
(9/25)G = 21 + 4 -8/5
(9/25)G = 117/5
G = (117/5) ( 25/9) = 65
John must have started with (3/5)G + (3/5)G - 4 = (6/5)(65) - 4 = 74
Kaden must have started with G + (2/5)[ (3/5)G - 4] = 65+ (2/5) [ (3/5)(65) - 4 ] =
65 + (2/5) [ 35] =
65 + 14 =
79
Proof
John started with 74 and gave away (3/5)(65) = 39
So he had 35 left
Kaden started with 79 and gave away 65
So....he had 14 left
And
35 -14 = 21