Ava is 9 years old. rose is 11 time as old as ava. how old is rose?

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry

Yo need asap pls ! markin da brainiest too !

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b