First it would help if you'd learn some LaTeX, so people can actually read what you've posted...
I assume it's
i'm trying to work out what steps i need to take to calculate the number that makes the following true...
(719 + 728 + 692 + 719 + X) / 5 = (719 + 728 + X) / 3
i know the answer is about 670 but don't know how to work it out.
can anyone help?