(1)1.69÷1.3+2.5×0.4,
=1.3+1,
=2.3;
(2)375+450÷18×25,
=375+25×25,
=375+625,
=1000;
(3)2×1.4+2×1.6,
=2×(1.4+1.6),
=2×3,
=6;
(4)83×102-83×2,
=83×(102-2),
=83×100,
=8300.
(1)1.69÷1.3+2.5×0.4,
=1.3+1,
=2.3;
(2)375+450÷18×25,
=375+25×25,
=375+625,
=1000;
(3)2×1.4+2×1.6,
=2×(1.4+1.6),
=2×3,
=6;
(4)83×102-83×2,
=83×(102-2),
=83×100,
=8300.