S/A=4.5,D/A=4.5, N/E =.80

& A = D + E solve for N/S

S=4.5A and D=4.5D, so S=D

N=.8E
A=D+E

So A=S+E=S+N/.8

dividing by S
A/S=1+N/S (1/.8)

but A/S=1/4.5 so solve for n/s

im still confused.

Bob meant to write:

S=4.5A and D=4.5A, so S=D

What other steps are confusing you?

You end up with
A/S = 1 + (N/S)(1/.8)
but you already knnow that

A/S = 1/4.5 , so
so solve for N/S.

(N/S)*(5/4) = (A/S) -1
= (2/9)- 1 = -7/9
N/S = (4/5)(-7/9) = -28/45

Check my math

To solve for N/S, we need to first calculate the values of N, S, A, D, and E using the given information:

Given:
S/A = 4.5
D/A = 4.5
N/E = 0.80

Also, we have the equation A = D + E.

Let's break down each step to solve for N/S:

Step 1: Rearrange the equation A = D + E to solve for E.
A = D + E --> E = A - D

Step 2: Substitute the value of E into the equation N/E = 0.80.
N/(A-D) = 0.80

Step 3: Substitute the values of S/A = 4.5 and D/A = 4.5 into the equation N/(A-D) = 0.80.
N/(4.5A-A) = 0.80

Step 4: Simplify the expression.
N/3.5A = 0.80

Step 5: Multiply both sides of the equation by 3.5A to isolate N.
N = 0.80 * 3.5A
N = 2.8A

Step 6: Substitute the value of A in terms of D and E into the equation N = 2.8A.
N = 2.8(D + E)

Step 7: Substitute the given equation S/A = 4.5 into the equation N = 2.8(D + E).
N = 2.8(D + E) = 2.8(4.5D + 4.5E)

Step 8: Multiply and distribute the values.
N = 12.6D + 12.6E

Step 9: Rearrange the equation to solve for N/S.
N/S = (12.6D + 12.6E) / S

Now, to find the value of N/S, you need to know the specific values of D, E, and S. Plug in those values into the equation N/S = (12.6D + 12.6E) / S to calculate the result.