In the following figure, rectangle represents brand managers, circle represents cartoonist, triangle represents sculptors and square represents fathers. Which set of letters represents fathers who are either brand managers or cartoonists?
7 workers work in a printing press. Each gets paid Rs 450 per day. The 8th worker demands Rs 500 per day. If this worker is hired then all other workers must be paid Rs 500. The marginal resource (labour) cost of the 8th worker is _______.