A:y=7(3≥x>0) y=7+1.2(x-3)(x>3);B:y=5(3≥x>0) y=5+1.5(x-3)(x>3);所以这样看来,当x<29/3千米时按b方案坐车;当x≥29/3时乘坐A方案;这就是算式了,要不具体的自己算一下就好了...
A型车费:7+1.2(X-3)=1.2X+3.4B型车费:5+1.5(X-3)=1.5X+0.5差价为:1.2X+3.4-(1.5X+0.5)=-0.3X+2.9