which of the following numbers should replace the missing denominator in order to add the fractions 25 over 80 + 13 over ?
To add fractions, we need to have a common denominator. Let's find the missing denominator:
The denominators of the given fractions are 80 and an unknown denominator. The smallest number that is divisible by both 80 and 1 is their least common multiple (LCM).
The prime factorization of 80 is 2^4 * 5.
By examining the prime factorizations, we see that the LCM is 2^4 * 5 = 16 * 5 = 80.
Therefore, the missing denominator should be 80.
So, the correct fraction to replace the missing denominator is 13/80.
The addition of the fractions 25/80 + 13/80 would then be equal to:
25/80 + 13/80 = (25 + 13)/80 = 38/80.