(1)
×3.5+5.5×80%+0.84 5
=0.8×3.5+5.5×0.8+0.8
=0.8×(3.5+5.5+1)
=0.8×10
=8
(2)0.5+
×(0.15+5 6
)9 20
=0.5+
×(0.15+0.45)5 6
=0.5+
×0.65 6
=0.5+0.5
=1
(3)98.47-(65.47-4.6)-4.6
=98.47-65.47+4.6-4.6
=(98.47-65.47)+(4.6-4.6)
=33+0
=33
(4)
×3 4
+0.25×2 7
2 7
=
×3 4
+2 7
×1 4
2 7
=(
+3 4
)×1 4
2 7
=1×
2 7
=
2 7