Răspuns :
sunt doua metode 1+20+2+19+3+18+4+17+5+16+6+15+7+14+8+13+9+12+10+11= 21+21+21+21+21+21+21+21+21+21= 41+41+41+41+41=82+82+41=164+41=205
si a doua e prin simplificare
si a doua e prin simplificare