Answer:
Just substitute, and the simplified form is 1
Explanation:
Substitute the values needed into the original equation. For example, if n=1
t(1)=15-2.5(1)=15-2.5=12.5. Or, if tn+1 substitute f(tn+1)=15-2.5(tn+1) and simplify.
tn+1-tn in its simplest form is just 1, as tn and -tn cancel out to leave 1.