There is a picture below of the number line with the numbers, plotted.
For the 2 3/8, you would simply go to 2 and count 3 to the right because there are 8 points for each whole number to the next. For 1 3/4, you would make the denominator 8, so multiply it by 2. When we do this, we multiply both the numerator and denominator. What is done to one must be done to the other. 3*2 to get 6. 4 x 2 to get 8. So, 3/4 becomes 6/8. Now, we can go to 1, and count 6 points to the right to get to 1 3/4.