(1).(1/2a+1/3b)/(2/3a-1/4b)
=(6a+4b)/(8a-3b) (分子分母同乘以12)
(2)(4/5x+0.25y)/(1/2x-0.6y)
=(16x+5y)/(10x-12y) (分子分母同乘以20)