We can express this numbers as comparable fractions:
We will keep 10 7/10 as it is, but express 10 4/5 as:
Then, we can see that 10 4/5 = 10 8/10 and that is higher than 10 7/10.
He was not correct when writing the inequality like that.
The right inequality is 10 7/10 < 10 4/5.
We can draw it in a line as:
If we divide the space between 10 and 11 in ten parts, the seventh spot corresponds to 7/10, and the eighth spot (or the fourth, if we divide the space in fifths) corresponds to 8/10=4/5.