Consider program p, which runs on a 4 ghz machine m in 200 seconds. consider an optimization to p that replaces all instances of multiplying a value by 4 (mult x, x,4) with two instructions that set x to x x twice (add x, x; add x, x). assume that every multiply instruction takes 6 cycles to execute, and every add instruction takes just 1 cycle. after recompiling, the program now runs in 150 seconds on machine m. determine how many multiplies were replaced by this optimization.