X Company must decide whether to continue using its current equipment or replace it with new, more efficient equipment. The current equipment will last for six more years and has a current disposal value of $14,000. The new equipment will cost $164,000 and will also last for six years. Operating costs with the current equipment are $66,500 and operating costs with the new equipment are $34,050. If X Company replaces the current equipment, what is the approximate internal rate of return?

I did: 164,000-14,000=150,000/(66,500-34,050)=4.622, so I said the IRR is 8%. It's not correct, what did I do wrong?