Which expression is equivalent to b^-3/ab^-3?

Points d and e are midpoints of the sides of triangle abc. the perimeter of the triangle is 48 units. what is the value of t? ο ο ο ο 7t +

Nell has a sales clerk job that pays $12 per hour for regular gas work hours. she gets double time for any hours over 40 that she works in a week. how many hours did nell work if her weekly pay was $744

What is the missing step in this proof ?