Уравнение. 84a+25a+7=443. 4(9+7x)21=393. 486:(5x+2)=18. 5(14+ b)+6b=258

1. 84 * a + 25 * a = 443 – 7;109 * a = 436;a = 436/109 (по пропорции);a = 4.2. 4 * 9 + 4 * 7 * x + 21 = 393;36 + 28 * x + 21 = 393;28 * x = 393 – 36 – 21;28 * x = 336;x = 336/28 (по пропорции);x = 12.3. (5 * x + 2) * 18 = 486 * 1 (по пропорции);5 * x * 18 + 2 * 18 = 486;90 * x + 36 = 486;90 * x = 486 – 36;90 * x = 450;x = 450/90 (по пропорции);x = 5.4. 5 * 14 + 5 * b + 6 * b = 268;70 + 5 * b + 6 * b = 268;5 * b + 6 * b = 268 – 70;11 * b = 198;b = 198/11 (по пропорции);b = 18.