一又二分之一×七分之五-(-七分之五)×二又二分之一+(-2/1)÷一又五分之二
=1又1/2×5/7+5/7×2又1/2-2×5/7
=5/7×(1又1/2+2又1/2-2)
=5/7×2
=10/7
=1又3/7