`a, 49^{5} : 7^{6}`
`= (7^{2})^{5} : 7^{6}`
`= 7^{10} : 7^{6}`
`= 7^{4}`
____________________
`b, (3/4)^{23} : (9/16)^{5}`
`= (3/4)^{23} : [(3/4)^{2}]^{5}`
`= (3/4)^{23} : (3/4)^{10}`
`= (3/4)^{13}`
_____________________
`c, 3^{2} . 1/3 . 9^{2}`
`= 9 . 1/3 . 9^{2}`
`= 9 . 9^{2} . 1/3`
`= 9^{3} . 1/3`
`= 729 . 1/3`
`= 243`
