MATLAB: How to assign value to variable

MATLAB

My equation is Y+5 = 10, how can i assign value to Y because i keep getting this error.

You cannot assign value to variable like this. The correct syntax is

y = 10 - 5;

Only variable name can be on left side. I suggest taking this free course to understand the basics of MATLAB: https://www.mathworks.com/learn/tutorials/matlab-onramp.html

if rand < probability
  A1 = A2;
end

It is not possible in one statement. It is possible in two statements, which you could combine on one line.

t = num2cell([1,2,3,4]);
[a,b,c,d] = deal(t{:});