Richard is 15th from the front in a column of boys. There were thrice as many boys behind him as there were in front. How many boys are there between Richard and the seventh boy from the end of the column?
Number of boys in front of Richard = 14
Number of boy behind Richard = 14x3 = 42
∴Total number of boys in the column = 14+1+42 = 57
In a column of 57 boys, the 7th boy from the end is clearly 51st from the start. Thus, we have to find the number of boys between the 15th and the 51st boy, which is 35.