( 7a - 4,5b ) - ( 2,5a + 1,5b ) = 7a - 2,5a - 4,5b - 1,5b = 4,5a - 6b
a = 1
b = 1
4,5 * 15/11 - 6 * 4/3 = 9/2*15/11 - 8 = 135/22 - 8 = - 41/22 = -1,863
( 7a - 4,5b ) - ( 2,5a + 1,5b ) = 7a - 2,5a - 4,5b - 1,5b = 4,5a - 6b
a = 1
b = 1
4,5 * 15/11 - 6 * 4/3 = 9/2*15/11 - 8 = 135/22 - 8 = - 41/22 = -1,863