Are You Clever Enough To Solve This? : 6 _ 3 _ 9 _ 9 = -7

This puzzle necessitates rapid thinking and problem solving aptitude. You'll be given a formulae with three operators missing. Your task is to locate the absent operators and fill in the formulae. It's a superb way to evaluate your understanding of basic mathematics and enhance your reasoning skills. Prepare to exercise your intellect and have fun!