I-5又1/2I×(1/2-1/3)×3/11÷(-1又1/4)×(-2)^2÷(-5)
=I-5又1/2I×(1/2-1/3)×3/11÷(-1又1/4)×4÷(-5)
=11/2×1/6×3/11×(-4/5)×4×(-1/5)
=4/25