Suppose A-D=E, thAt N= 15,200, E/A= .40 and N/E=.25. compute D/A

Answer 1

as N/E = .25, N = .25 * E
-> E = 60,800 as 15,200 = .25 * E

as E/A = .40, E = .40 * A
-> A = 152,000 as 60,800 = .40 * A

as A - D = E, - D = E - A
as - D = - 91,200, D = 91,200

-> D/A = 91,200 / 152,000 = .60

Answer 2

easier way:
A-D=E , divide each term by A
A/A - D/A = E/A
1 - D/A = .40
1 - .40 = D/A
D/A = .60

N never entered the picture.