I've started two step equations and i'm lost me.

The sum of two numbers is 86, and their difference is 20. find the two numbers

Barney & noblet customers can choose to purchase a membership for $25 per year members receive 10% off all store purchases 1. how much would a member pay per year if he bought $50 worth of items each year? 2. write a slope-intercept equation that expresses how much a member pays per year using x to represent his purchases per year 3. how much would a member have to spend per year to pay off his membership fee?

Divide. –4.2 ÷ 6 = a –0.7 b 0.7 c –7 d 7 me