✔ 最佳答案
樓上為人兄計錯了A
8A +17B = 299.8--------(1)
9A+13B = 284.6---------(2)
(1) - (2) : (8A +17B) - (9A+13B) = 299.8 - 284.6
: 8A + 17B - 9A - 13B = 15.2
: -A + 4B = 15.2
: A = 4B - 15.2 ---------(3)
將(3) 代入 (2)
9A+13B = 284.6
9(4B - 15.2) +13B = 284.6
36B - 136.8 + 13B = 284.6
49B - 136.8 = 284.6
49B = 284.6 + 136.8
49B = 421.4
B = 421.4/ 49
B = 8.6
將B = 8.6代入(3)
A = 4B - 15.2
A = 4(8.6) - 15.2
A = 34.4 - 15.2
A = 19.2
總結:A=19.2, B=8.6