solve a equation in matlab with variable -

i'm trying use 'solve' method solve equations in matlab , have matrix coefficients of variables in called 'a'

but when use solve method code (i want a(1,1) coefficients x variable) :

w0 = solve('a(1,1)*x+13*y-16*z=1','13*x-10*y+13*z=0','-16*x+13*y-7*z=0') w0 = [w0.x w0.y w0.z] 

i dont correct answer , shows me answer:

[ 11/(11*a(1, 1) + 185), 13/(11*a(1, 1) + 185), -1/(11*a(1, 1) + 185)] 

meaning value of a(1,1) not recognized in code, can me getting right answer?

how about

w0 = solve([num2str(a(1,1)),'*x+13*y-16*z=1'],'13*x-10*y+13*z=0','-16*x+13*y-7*z=0')