化简 6a+13a 6x-28-2.5x+30.5 8a-(5a+8) 5x+7-(4x+0.18)

问题描述:

化简
6a+13a   

6x-28-2.5x+30.5

8a-(5a+8)

5x+7-(4x+0.18)

①6a+13a=19a②6x-28-2.5x+30.5=6x-2.5x+30.5-28=(6x-2.5x)+(30.5-28)=3.5x+2.5③8a-(5a+8)=8a-5a-8=3a-8④5x+7-(4x+0.18)=5x+7-4x-0.18=5x-4x+7-0.18=(5x-4x)+(7-0.18)=x+6.82