How would i solve this? i have to find extraneous solutions along with it

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

The table shows how many people went on a roller coaster during 3 days. sean wants to know if the total of number of people is greater than 800. how can you answer sean's question without actually computing the total? explain. friday 158 people, saturday 292 sunday 278

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