(1) 4x + 3y = 24 (1)5x - y = 30 (1)解 (1）+（2）×3 得 19x = 114 解得 x = 6把x = 6代入（1）得 y = (24 -4×6)/3 = 0所以 x = 6 ,y = 0(2) 2.5x + 3y = 8 (1)7x - 3y = 4 (2)解 （1）+（2）得 9.5x = 12,解得 x...