n(S): Choose 4 distinct digits from {0,1,…,9} and arrange in decreasing order. n(S)=(410)=210.
n(P): 5-digit numbers with digit product =20=22×5. All digits ≥1 (else product =0). Must include exactly one 5, remaining 4 digits multiply to 4.
Case 1: {1,1,1,4,5}: 3!5!=20 arrangements.
Case 2: {1,1,2,2,5}: 2!⋅2!5!=30 arrangements.
n(P)=50. Hence n(S)+n(P)=210+50=260.