(1)12.53-1.35×2-9.3
=12.53-2.7-9.3
=12.53-(2.7+9.3)
=12.53-12
=0.53
(2)0.8×（4-3.75）÷0.1
=0.8×0.25÷0.1
=0.2÷0.1
=2
(3)13.5×0.68÷8.5
=13.5÷5×（0.68÷1.7）
=2.7×0.4
=1.08
(4)20-【7.8+（6.2+1.29）】
=20-【7.8+6.2+1.29】
=20-【14+1.29】
=20-15.29
=4.71