A $78.00 pair of shoes cost $84.63 after tax is added. What is the tax rate?

Ineed to know the answer to this algebra question.

Luke started a weight-loss program. the first week, he lost x pounds. the second week, he lost pounds less than times the pounds he lost the first week. the third week, he lost 1 pound more than of the pounds he lost the first week. liam started a weight-loss program when luke did. the first week, he lost 1 pound less than times the pounds luke lost the first week. the second week, he lost 4 pounds less than times the pounds luke lost the first week. the third week, he lost pound more than times the pounds luke lost the first week.

What is the length of the midsegment of a trapezoid with bases of length 15 and 25 ?