13. at a certain laboratory, chemical substances are identified by an unordered combination of 3 colors. if no chemical may be assigned the same colors, what is the maximum number of substances that can be identified using 7 colors?

Geometry: determine whether segment mn is parallel to segment kl. justify your answer. jm 6 mk 3 jn 8 nl 4

Sunday: 1 1 2 monday: 1 tuesday: 2 1 2 wednesday: 1 3 4 thursday: 2 friday: 1 1 2 saturday: 2 jenna is a swimmer and trains every day. the schedule shown outlines the number of hours she trains each day. what is the total number of hours that jenna trains during the week?

Given: pqrs is a parallelogram prove: pr and qs bisect each other at t