Răspuns :
20+(1+2+...+100)-(1+2+...+10)
20+(101x100:2)-(11x10:2)
20+(101x50)-(11x5)
20+5050-55=20+4995=5015
20+(101x100:2)-(11x10:2)
20+(101x50)-(11x5)
20+5050-55=20+4995=5015