how can we write 99 and 49 in roman numerals?

99 = 90 + 9  

Roman numeral for 90 = XC

Roman numeral for 9 = IX

So, 99 = XCIX.

49 can be written as 40 + 9

Roman numeral for 40 = XL

Roman numeral for 9 = IX

So, 49 = XLIX.