You need to read the data into MATLAB with xlsread() or readtable(). Then extract the appropriate column into variables h and TR, and define n1, n2, and n3:
numbers = xlsread(filename);
h = numbers(:, 8); % Or whatever.
TR = numbers(:, 9); % or wherever it is....
n1 = 1; % Whatever it is.
n2 = 2; % Whatever it is.
n3 = 3; % Whatever it is.
N1=sum(h(4:23))/20
N2=(19*n1 +TR(2))/20
N3=(19*n2 +TR(3))/20
N4=(19*n3 +TR(4))/20
