\[a = 4,625 \approx 4,63;\ \ \ \ \ \]
\[b = - 5,(6) \approx - 5,67\]
\[a + b = 4,63 + ( - 5,67) =\]
\[= 4,63 - 5,67 =\]
\[= - (5,67 - 4,63) = - 1,04\]
\[a - b = 4,63 - ( - 5,67) =\]
\[= 4,63 + 5,67 = 10,30\]