(1)（3.8－1.8÷2）×0.3
=（3.8-0.9)x0.3
=2.9x0.3
=0.87
(2)2÷2/3－2/3÷2
=2x3/2-1/3
=3-1/3
=2又2/3
(3)（15－15×4/5）×7/24
=15×（1-4/5）×7/24
=15×1/5×7/24
=3×7/24
=7/8