19/38 and 15/18
Explanation:
19/38 can be reduced as there is a factor other than 1 that can divide without a remainder. Factor is 19
It can still be reduced because 19*2 = 38
19/38 = 1/2
10/19 cannot be reduced as there is no factor other than one to divide without a remainder
21/34 cannot be reduced as there is no factor other than one to divide without a remainder
15/18 can be reduced as there is a factor other than 1 that can divide without a remainder.
The factor is 3
15/18 = 5/6
Fraction that has not been reduced to simplest form are 19/38 and 15/18
