What expression represents the sum of 8 and twice a number

Ibeg you to me 20. a reaction produces 4.93 l of oxygen, but was supposed to produce 1 mol of oxygen. what is the percent yield?

Geometry - finding area of regular polygons and sectors (check my math, i can’t find the error)

Agroup of five people go out to eat and buy appetizers and main dishes they decide to split the bill so each person pays 20% of the total cost appetizers are $5 and main dishes are $10 write an expression to show how much each person pays explain it with how to solve the problem