The wait time and distance count as a whole and since they don't wanna round down ( they don't wanna even give a free centimeter ) as they suggest you shoud use ceil and the code should be like this:
function a = taxi_fare(d, t);
first_km_cost = 5;
additional_km = 2;
time_cost = 0.25;
%% this is what you are missing
d = ceil(d); % ceil rounds any number to the nearest integer greater than or equal to that number
t = ceil(t);
%% rest
x = d-1; y = t;
a = first_km_cost + (x*additional_km) + (y*time_cost) % you don't need the parentheses but I kept them since you had it
end
