Astereo was sold for $270 after it was reduced by ⅓ of the original price. what is the original price?

Me because some of question i don’t understand

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

Can someone me with my math problems i have a bunch. i will give brainliest and lots of pleeeaaasssee