1. а) -450+705=255
б) -8.4+3.7=-4.7
в) -7+(-2
) = -7-2 = -9
г) 
+(-
) = - = 
- = 
д) 5
+(-7
) = 5-7 = 5
-7 = -2
2. а) -2.5+(-5.45) = -2.5-5.45 = -7.95
б) -2.5+12 = 9.5
в) -2.5+3
= -2.5+3.5 = 1
3. (-+
)+0.8 = (-0.5+62.5)+0.8 = 62+0.8 = 62.8
