(Xi - Ux)^2 + (Yi - Uy)^2 + (Zi - Uz)^2 = (ri - Cb)^2

this is what i put in mathematica

NSolve[ {(X1 - U)^2 + (Y1 - V)^2 + (Z1 - W)^2 - (R1 - B)^2 ==

0, (X2 - U)^2 + (Y2 - V)^2 + (Z2 - W)^2 - (R2 - B)^2 ==

0, (X3 - U)^2 + (Y3 - V)^2 + (Z3 - W)^2 - (R3 - B)^2 ==

0, (X4 - U)^2 + (Y4 - V)^2 + (Z4 - W)^2 - (R4 - B)^2 == 0}, {U, V,

W, B}]

and I either get an error or it takes forever to run (ive left it running for ten mins while im posting this)

anyone knw where im goin wrong if i am?