Question

a bank teller had $2750 in 10 dollar bills and5 dollar bills he had twice as many10 dollar billsas 5 dollar bills how many of each bill does he have

Answer 1

let x = the number of $5 bills.
let y = the number of $10 bills.

"a bank teller had $2750 in 10 dollar bills and5 dollar bills"
5x + 10y = 2750

"he had twice as many 10 dollar bills as 5 dollar bills"
y = 2x

Solve for x and y. Substitution is likely easiest.