What is the conjugate of 7-8i?

What is the approximate circumference of the circle shown below?

Mary used 1/7 of a spool of ribbon to complete 4 projects. she used the same amount of ribbon on each project. how much ribbon did she use on each project?

Pam buys a sleeve of ball bearings for her skateboard. each of the bearings is 1 1/5 inches wide. the sleeve is 9 3/5 inches long. how many ball bearings are in the sleeve? show your work.