(1)1又4/5×1.25+1又1/4×2.2-1又1/4
=1又1/4×(1.8+2.2-1)
=5/2
=2又1/2
2)13/5×8×8/13×1.25
=13/5×8×8/13×5/4
=32
3)4-4/5÷4-4/5
=4(1-1/5)-4/5
=4/5-4/5
=0
4)3/8÷[(1/5+1/4)×3/8]
=1÷(4/20+5/20)
=20/9
(1)1又4/5×1.25+1又1/4×2.2-1又1/4
=1又1/4×(1.8+2.2-1)
=5/2
=2又1/2
2)13/5×8×8/13×1.25
=13/5×8×8/13×5/4
=32
3)4-4/5÷4-4/5
=4(1-1/5)-4/5
=4/5-4/5
=0
4)3/8÷[(1/5+1/4)×3/8]
=1÷(4/20+5/20)
=20/9