Question

After a trip to monticello, randall had a number of $1 and $2 bills in his pocket. if he had 13 bills worth a total of $15, how many bills did he have of each type?

Answer 1

$x$ ones, $y$ twos

$x+y=13$

$x+2y=15$

Subtracting,

$2y - y = 15 - 13$

$y=2$

$x=13-y=11$

11 ones, 2 twos, thirteen bills, fifteen dollars, check.