Sam does 11 jumping jacks in 8 seconds. If he does the jumping jacks at a constant rate, how many jumping jacks can he do in 20 seconds?

When george started his current job, his employer told him that at the end of the first year, he would receive two vacation days. after each year worked, his number of vacation days will double up to five work weeks (25days) of payed vacation. how many vacation days will he have in 4 years