I will do 6/8 only. You do the other fraction.
Pick a number, any number. How about 2?
Multiply the top and bottom number by 2.
6 x 2 = 12
8 x 2 = 16
We get 12/16.
Reducing 12/16 to the lowest terms we get 3/4.
Another fraction similar to 6/8 is 3/4. In fact, they are equivalent fractions.
Do the other fraction in like fashion.
Note: Each fraction given has more than one similar fraction.