(1)4.32-2.5+1.89
=1.82+1.89
=3.71;
(2)13.58-(4.56+3.58)
=13.58-3.58-4.56
=10-4.56
=5.44;
(3)4.5×0.7+5.5×0.7
=(4.5+5.5)×0.7
=10×0.7
=7;
(4)82.4-12.4×5
=82.4-62
=20.4.
(1)4.32-2.5+1.89
=1.82+1.89
=3.71;
(2)13.58-(4.56+3.58)
=13.58-3.58-4.56
=10-4.56
=5.44;
(3)4.5×0.7+5.5×0.7
=(4.5+5.5)×0.7
=10×0.7
=7;
(4)82.4-12.4×5
=82.4-62
=20.4.