ALGERA
posted by JOHN on .
ASSUME THAT S/A= 4.5, D/A= 4.5, N/E= .80 AND A=D+E SLOVE FOR N/S.

Well, from the first two, D=S
and D=4.5A
From the fourth,
A=D+E=4.5A+E
or E=3.5A
But N=.8E, so N=.8*(3.5A)
solve for N/S is the same as N/D
N/s=N/D=.8*(3.5A)/4.5A
and surely you can finish it. 
is .62 correct

It is if you checked my work and found no errors.