To convert from a mixed number to an improper fraction, we take the whole number (75) and multiply it with the denominator of your fraction (3), and then add the numerator (1). Then we write it over your original denominator. So 75 1/3 = ((75 * 3) + 1) / 3 = 226 / 3. Now we need to write this in the lowest form. Since the only factors of the denominator are 1 and 3, we simply check to see if the 3 can go into the 226 evenly (since 1 goes into all numbers, we don't worry about it). Now there is a shortcut to see if 3 can go into a number. Simply add up the digits of the number, and if 3 can go into the new number, it will go into the original number. So for 226, 2 + 2 + 6 = 10. Since 3 can't go into 10, it won't go evenly into 226. At this point, 226 / 3 is the fraction in simplest terms.