It looks like you have 6 equations and 7 unknowns:
Solve[{10.109*w - d*200 - 0.788*500 - 1.231*4*x5 + 16.296*101.8 - 1.231*x4 == 0,
101.8 - 4*x5 - 2*x3 - x4 - x2 == 0,
y1 + w - 500 - 200 == 0,
x5 == 0.563*x3,
x4 == x2,
1.5*x4 == x5},
{x2, x3, x4, x5, y1, w, d}]
which results in
{{x2 -> 7.63771, x3 -> 20.3491, x4 -> 7.63771, x5 -> 11.4566,
w -> 700. - 1. y1, d -> 41.3771 - 0.050545 y1}}
