I really don't get what I'm supposed to do...​

Luisa sells stuffed animals. she sells her stuffed elephant for $34.90, and the sales tax is 6% of the sale price. about how much is the sales tax on the elephant?

The half-life of iodine-131 is approximately 8 days. find the amount of iodine-131 left from a 42 gram sample after 16 days. a: 10.5 grams b: 21 grams c: 0.0006 grams d: 34 grams

15 ! will give ! 1. simplify 100 squared. a 20 b 10 (pretty sure it's 10) c 50 d 25 2. simplify 27/12 squared a 13/6 b 2/3 c 3/2 (pretty sure it's 3/2) d 3 3. find the square root of 0.49 a 7 b 0.07 c 0.007 d 0.7 (almost completely sure its 0.7) 4. simplify fully. 2 5 squared + 3 5 squared - 5 squared a 5 5 squared (pretty sure its this one) b 4 5 squared c 5 15 squared d 4 15 squared 5. simplify 2 squared * 800 squared a 20 b 40 c 80 d 400