Steve got his car fixed for $557. after taxes it cost him $594. what was the tax rate to the nearest %? -what i have so far-bill: $557total: $594557·x=594 (solve and round to nearest %)

You're nearly there. Just some more steps.
557 * x = 594 tells us 
x = 594 / 557 (divide both sides by 557)
x ≈ 1.066427

When we've found this number we must realise the following:
the '1' in this answer is the 100% the car fixing costs (without taxes)
the '0.66427' stands for the tax rate.

To find the tax rate we multiply 0.66427 by 100, which gives us:
0.66427 * 100 = 6.6427 ≈ 7

So, rounded to the nearest %, the tax rate is 7%