Thank you for your advice, Bill Simpson, but it doesn't seem to work the way I'd like. I'll give you the whole code:
(*Definiton of equations*)
r1 = nF1 == nD1 + nW1;
r2 = xAF1*nF1 == xAD1*nD1 + xAW1*nW1;
r3 = nW1 == nD2 + nW2;
r4 = xAW1*nW1 == xAD2*nD2 + xAW2*nW2;
r5 = nW2 == nD3 + nW3;
r6 = xAW2*nW2 == xAD3*nD3 + xAW3*nW3;
(*Known parameters*)
xAF1 = 0.2308;
xAD1 = 0.9990;
xAW1 = 0.1589;
xAD2 = 0.9941;
xAW2 = 0.0865;
xAD3 = 0.3171;
xAW3 = 0.03353;
nW3 = 9932.42;
(*Solving of the unknown parameters*)
vars = {nF1, nD1, nW1, nD2, nW2, nD3};
vars = vars /. Solve[{r1, r2, r3, r4, r5, r6}, vars]
(*Here is the part for using solved variables*)
nAF1 = xAF1*nF1
nAD1 = xAD1*nD1
nAW1 = xAW1*nW1
nAD2 = xAD2*nD2
nAW2 = xAW2*nW2
nAD3 = xAD3*nD3
But my ouput still looks like this:
Out[1]= {{14515., 1242.27, 13272.7, 1058.78, 12213.9, 2281.53}}
Out[2]= 0.2308 nF1
Out[3]= 0.999 nD1
Out[4]= 0.1589 nW1
Out[5]= 0.9941 nD2
Out[6]= 0.0865 nW2
Out[7]= 0.3171 nD3
As you can see, it doesn't work since the variables which the equations are solved for aren't assigned. What am I doing wrong? Thank you
P. S. I know these are simple equations but Mathematica is new to me so I try to use it as much as possible to get used to it, and solution of this problem could be useful in the future.