If p/h dies in month n, benefit is 7000-100n. So premium earned in month n is proportional to 70-n. The sum of these weights over the term of the policy from n = 0 to n = 59 is 60*70-(60*59)/2=2430 (using the sum of an arithmetic progression). After m months the proportion of risk remaining is sum(from m to 59) of (70-n)/2430. So UPR is that times 20 euro. The examiners's report goes on to expand this and comment on an 'exact' calculation, but hopefully this wouldn't be necessary to score full marks.
