用递等式计算（能简算要简算）3.6+2.7+6.4；15-3.28-1.72；6.08-1.5+0.92；4.6-（1.45+2.15）．

Question

用递等式计算（能简算要简算）
3.6+2.7+6.4；       15-3.28-1.72；        6.08-1.5+0.92；        4.6-（1.45+2.15）．

Answer 1

（1）3.6+2.7+6.4
=（3.6+6.4）+2.7
=10+2.7
=12.7；

（2）15-3.28-1.72
=15-（3.28+1.72）
=15-5
=10；

（3）6.08-1.5+0.92
=6.08+0.92-1.5
=7-1.5
=5.5；

（4）4.6-（1.45+2.15）
=4.6-3.6
=1．