(1)2.38×6.8+7.62×6.8,
=(2.38+7.62)×6.8,
=10×6.8,
=68;
(2)12.5×4-3.12÷1.2,
=50-2.6,
=47.4;
(3)26.8-(4.2+2.6)×1.5,
=26.8-6.8×1.5,
=20+6.8-6.8×1.5,
=20-(1.5-1)×6.8,
=20-0.5×6.8,
=20-3.4,
=16.6;
(4)15.84÷[0.8×(7.93-2.43)],
=15.84÷[0.8×5.5],
=15.84÷4.4,
=3.6.