小明和小华做题的速度比
=[1/3+(1-1/3)×1/2]:(1/2)
=(1/3+1/3):(1/2)
=(2/3):(1/2)
=4:3
总题数
=45÷(1-1/3×3/4)
=45÷(3/4)
=60(道)