First of all, divide it in half: 7.375". Now you only have to divide by 19.
Divide by 20 and note the approximate result: 0.7375 is division by 10, and 0.37 (dividing by 2) is a further approximate division by 20. This is an estimate of the answer when divided by 19. Ignore the decimal point and divide by 19 using direct division or long division. Your estimate gives you a clue: 3*19=57; 73-57=16; 19 into 167 goes 8, 8*19=152; 167-152=15; 150/19 is almost 8*19, so we have the figures 388 approximately and putting in the decimal point using the estimate we have 0.388" as the approximate answer. A more accurate answer would be 0.38816".