What is 12% of 30 i don't know this question at all

Tcan be concluded that % of the seniors would prefer to see more candid pictures in this year's edition of the yearbook.

Kathy spent 5/8 of her money on books and another 1/6 of her money on stationeries. what fraction of kathy’s money was left?

At the electronics store you have a coupon for 20% off up to 2 cds you buy for cds with the original cost of $10.99 each the sales tax is 5% what is the total cost of your purchase