Answer:
x= Dan's marbles
Leah = x+28
I translate the statement in math by this equation:
(x+28)/3 = 4x/5
3*4x = 5(x+28)
12x = 5x+140
12x-5x=140
7x= 140
x= 20
Dan has 20 marbles
Leah has 48 marbles
we check:
1/3 of Leah's number of marbles = 48/3 = 16 is equal to 4/5 of Dan's marbles: (20*4)/5=16