You can get symbolic solution by
syms K C V B N X
eq = K*(B-X)*(N-X)-(C+X)*(V+X);
x = solve(eq, X)
and the final process is
K = 1;
% There are two solutions, x1 is the first solution
x1 = @(C,V,B,N) (C + V - (B.^2.*K.^2 + 2*B.*C.*K - 2*B.*K.^2.*N + ...
4*B.*K.*N + 2*B.*K.*V + C.^2 + 2*C.*K.*N + 4*C.*K.*V - 2*C.*V + ...
K.^2.*N.^2 + 2*K.*N.*V + V.^2).^(1/2) + B.*K + K.*N)./(2*(K - 1));
% x1 is the second solution
x2 = @(C,V,B,K) (C + V + (B.^2.*K.^2 + 2*B.*C.*K - 2*B.*K.^2.*N + ...
4*B.*K.*N + 2*B.*K.*V + C.^2 + 2*C.*K.*N + 4*C.*K.*V - 2*C.*V + ...
K.^2.*N.^2 + 2*K.*N.*V + V.^2).^(1/2) + B.*K + K.*N)./(2*(K - 1));
C = rand(20,1); % randomly initialized data
V = rand(20,1);
B = rand(20,1);
N = rand(20,1);
X = x1(C,V,B,N); % choose the first answer of x, you can also choose the second
C_new = sort(C + X);
V_new = sort(V + X);
B_new = sort(B + X);
N_new = sort(N + X);
