10 4/7 as an improper fraction is 74/7.
You have to count how many 7's (wholes) are in 10 4/7 and then add the remainder, which is the numerator. The denominator stays the same at all times.
To check your answer you can divide 74 by 7 and see what you get.
74 / 7 = 10 4/7
Hope I was able to help! :) feel free to ask any questions below.