-(9.8+6.9)-(10,2-6.9) б)(1.59+3.47)-(2.47+0.59) в)(1.9+2.5)-(5.9-2.5) г)(0.85+1.5)-(-0.65-3.5)

Вычислим значения выражений:

a) -(9.8 + 6.9) - (10,2 - 6.9) = -9.8 - 6.9 + 10.2 + 6.9 = -9.8 + 10.2 = 10.2 - 9.8 = 0.2 + 0.2 = 0.4; 

б) (1.59 + 3.47) - (2.47 + 0.59) = 1.59 + 3.47 - 2.47 - 0.59 = (1.59 - 0.59) + (3.47 - 2.47) = 1 + 1 = 2; 

в) (1.9 + 2.5) - (5.9 - 2.5) = 1.9 + 2.5 - 5.9 + 2.5 = (1.9 - 5.9) + (2.5 + 2.5) = -4 + 5 = 1; 

г) (0.85 + 1.5) - (-0.65 - 3.5) = 0.85 + 1.5 + 0.65 + 3.5 = (1.5 + 3.5) + (0.85 + 0.65) = 5 + 1.5 = 6.5.