=7.2-3.6+3.6+2.5

=(7.2+2.5)+(-3.6+3.6)

=9.7+0

=9.7

2、(-72)-(-37)-(-22)- 17

=-72+37+22- 17

=(-72+22)+(37- 17)

=-50+20

=-30

3、0-(+3)-|-3.5|-(-4.2)

=0-3-3.5+4.2

=-3-3.5+4.2

=-6.5+4.2

=-2.3

4、 1/2-(- 1/2)-(-3/4)- 1/6

= 1/2+ 1/2+3/4- 1/6

= 1+3/4- 1/6

=7/4- 1/6

=2 1/ 12-2/ 12

= 19/ 12

= 1 and 7/ 12

5、2/3- 1/8-(- 1/3)+(-3/8)

=2/3- 1/8+ 1/3-3/8

=(2/3+ 1/3)-( 1/8+3/8)

= 1- 1/2

= 1/2