7fed8270b58669f751ee8ee043807473dc8ecd2293663dcfff890d92f40c7d

51-34 = (50+1)-(30+4) = (50-30) + (1-4) = 20-3 = 17

빌려오는 방식은
51-34 = (40+11)-(30+4) = (40-30)+(11-4) = 10+7 = 17