Melissa keeps a jar for holding change. the jar holds 21 coins. all of the coins are quarters and nickels. the total amount in the jar is $3.85. how many quarters are in the jar?

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