6a+13a
问题描述：
6a+13a
6x-28-2.5x30.5
8a-(5a+8)
(5x+7)-(4x+0.18)
答
(1)6a+13a
=(6+13a)
=19a
(2)6x-28-2.5x30.5
=6x-28-76.25
=6x-104.25
(3)8a-(5a+8)
=8a-5a-8
=3a-8
(4)(5x+7)-(4x+0.18)
=5x+7-4x-0.18
=5x-4x+7-0.18
=x+(7-0.18)
=x+6.82