Where am I making the mistake in my coding? Below attached is the instructions to follow. Can you please specify and correct the line in order to obtain desired result please?

syms x y; illum = 300/(4*pi*((x - 5)^2 + (y - 2)^2 + 3^2))  
ezcontourf(illum, [0 10 0 4]); colormap('gray'); axis equal tight  
subs(illum, {x, y}, {0, 0})
subs(illum, {x, y}, {5, 2})  
light2 = inline(vectorize('150/(4*pi*((x - d)^2 + (y - 2)^2 + 3^2))'), 'x', 'y', 'd')
[X,Y] = meshgrid(0:0.1:10, 0:0.1:4); contourf(light2(X, Y, 3) + light2(X, Y, 7), 20); colormap('gray'); axis equal tight  
contourf(light2(X, Y, 2) + light2(X, Y, 8), 20); colormap('gray'); axis equal tight  
contourf(light2(X, Y, 1) + light2(X, Y, 9), 20); colormap('gray'); axis equal tight  
d = 0:0.1:5; plot(d, light2(0, 0, d) + light2(0, 0, 10 - d))  
d = 0:0.1:5; plot(d, light2(5, 0, d) + light2(5, 0, 10 - d))  
hold on; plot(d, light2(0, 0, d) + light2(0, 0, 10 - d)); hold off  
syms d; eqn = inlinechar(light2(0, 0, d) + light2(0, 0, 10 - d) - light2(5, 0, d) - light2(5, 0, 10 - d)))
fzero(eqn, [0 5])  
light2(0, 0, 1.441) + light2(0, 0, 10 - 1.441)  
light3 = inline(vectorize('100/(4*pi*((x - d)^2 + (y - 2)^2 + 3^2))'), 'x', 'y', 'd')  
[X,Y] = meshgrid(0:0.1:10, 0:0.1:4); contourf(light3(X, Y, 1) + light3(X, Y, 5) + light3(X, Y, 9), 20); colormap('gray'); axis equal tight  
d = 0:0.1:5;  
for x = 0:0.5:5
plot(d, light3(x, 0, d) + light3(x, 0, 5) + light3(x, 0, 10 - d))
hold on
end
hold off  

[Image Analyst]

Well one glaringly obvious problem is making it hard to read by putting WAY too many commands/functions in a single line of code.

That, plus not indenting correctly. Type control-a, control-i to fix the indentation.