No
No.
It is greater than. 3/4 turns into 6/8.
"is greater than" >
Four ninths is less than eight sixteenths.
No.
Yes, four-fifths is greater than four-eighths.
Four fifths is less.
No, they are both a half.
no it is equal
Whether you are counting people, cookies, books, seventeenths, etc., fifteen is greater than four.
Eight does not go into four any whole number of times. In division, the number being divided (in this case, four) should be greater than the divisor (in this case, eight) for the division to result in a whole number quotient. Since eight is greater than four, it cannot go into four any whole number of times.
Convert them to the same denominator and the answer to your question will be immediately apparent (assuming you know that six is less than seven).