№1.
1) 645 - 596 * 971 - 847 = 645 - (596 * 971) - 847 = 645 - 578716 - 847 = (645 - 578716) - 847 = -578071 - 847 = -578918
2) 443 * 5 ÷ 128 + 315 * 86 = (443 * 5) ÷ 128 + (315 * 86) = 2215 ÷ 128 + 27090 = (2215 ÷ 128) + 27090 = 17,3046875 + 27090 = 27107,3046875