`a) 246 + [ 53 + (-246) + (-23)]`
`= 246 + [ 53 - 246 - 23]`
`=246 + 53 - 246 - 23`
`= ( 246 - 246) + ( 53 - 23)`
`= 0 + 30`
`= 30`
`b) \frac{2^12 . 13 + 2^12 . 65}{2^10 . 104} + \frac{3^10 . 11 + 3^10 . 5}{3^9 . 2^4}`
`= \frac{2^12 . ( 13 + 65)}{2^10 . 104} + \frac{3^10 . ( 11 + 5)}{3^9 . 2^4}`
`= \frac{2^12 . 78}{2^10 . 104} + \frac{3^10 . 16}{3^9. 2^{4}}`
`=\frac{2^2 . 78}{1 . 104}+ \frac{3^10 . 2^4}{3^9 . 2^4}`
`= \frac{4 . 78}{104} + \frac{3 . 1 }{1 . 1}`
`=312/104 + 3`
`= 3 + 3`
`= 6`
