Вправи 751 - 900 » 755

а) 75 – (Зх + 1) = 50; 3х + 1 = 75 – 50; 3х = 25 – 1; 3х = 24; х = 24 : 3; х = 8. б) 9(2х + 13) – 71 = 820; 9(2х + 13) = 820 + 71; 2х + 13 = 891 : 9; 2х = 99 – 13; 2х = 86; х = 43. в) (273 – 13х) : 17 + 30 = 43; (273 – 13х) : 17 = 43 – 30; 273 – 13х = 13 • 17; 13х = 273 – 221; 13х = 52; х = 4. г) 960 – 21(183 – 10х) = 267; 21(183 – 10х) = 960 – 267; 183 – 10х = 693 : 21; 10х = 183 – 33; 10х = 150; х = 15.