a. 3/7+(-5/2)+(-3/5)
= 3/7-5/2-3/5
=30/70-175/70-42/70
=-145/70-42/70
=-187/70
b. -8/18-15/27
= -4/9-15/27
= -12/27-15/27
= -27/27
= -1
c. 4/5-(-2/7)-7/10
=4/5+2/7-7/10
=56/70+20/70-49/70
=76/70-49/70
=27/70
d. 3,5-(-2/7)
=7/2-(-2/7)
=7/2+2/7
=49/14+4/14
=53/114