Lucy has enough money to go to Canada every 6 years, while Luke has enough to go every 9 years. If they pool their money, how often can they go?
Choose one:
A) 2 times per year	B) once every 15 years	C) 5 times every 18 years	D) 15 times a year	E) once every 7.5 years
Lucy's speed = 1/6 trips per year   Luke's speed = 1/9 trips per year   Lucy + Luke's speed= (1/6 + 1/9) = 5/18 trips per year   correct option is once every 15 years
<result>B</result>
Lucy has enough money to go to Canada every 6 years, while Luke has enough to go every 9 years. If they pool their money, how often can they go?