At lunch, the meal cost $55 and the sales tax of 3.58 was added to the bill. What was the tax rate for meals in this city?

I'm confused on this could anyone me and show me what i need to do to solve it.

If the sales price of a dvd is $20 and the markup is 34%, what is the cost of the dvd?

The edge of a cube was found to be 30 cm with a possible error in measurement of 0.4 cm. use differentials to estimate the maximum possible error, relative error, and percentage error in computing the volume of the cube and the surface area of the cube. (round your answers to four decimal places.) (a) the volume of the cube maximum possible error cm3 relative error percentage error % (b) the surface area of the cube maximum possible error cm2 relative error percentage error %