Question 189483
{{{3/7+x - 5/x = 4/7x}}}

If you get common denominators on the left side, then you can just cross multiply. (Think "common denominators" immediately when you see adding or subtracting fractions and you shouldn't get stuck with them.) I'd just multiply {{{3/7}}} by {{{x/x}}}, {{{x}}} by {{{7x/7x}}}, and {{{5x/x}}} by {{{7/7}}}. Then I'd add and subtract on the left side to get something cross-multiplyable. Is this a good start?