In USA the average I.Q. is 98 while the top one average I.Q. country is Hong Kong.
But the I.Q. distribution is given by a polinomial graph, few people with extremely low I.Q. 40~70, a lot between 70~100, some between 100~120, few between 120~140 and extremely low 140+
First, we simplify this to 3/4-j/12=0. 4/4=1 so we do, -j=-51/4*-1. Therefore, the answer is j=51/4. Hoped I helped. :)
OPTION C is the correct answer.
Hope it helps you.