How many groups of sixty are in two hundred forty-four

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

Prove the divisibility of the following numbers: 25^9 + 5^7 is divisible by 30.also, read as (25 to the power of 9) + (5 to the power of 7) is divisible by 30. blank x 30what is the blank? ( it should be expressed in exponent form)

Given: circle o, cd is diameter, chord ab || cd. arc ab = 74°, find arc ca.