i will mark you as the brainliest if you write it in a note book and send me fast . the question in the pic i sent

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

Given the system of equations presented here: 2x + 4y = 14 4x + y = 20 which of the following actions creates an equivalent system such that, when combined with the other equation, one of the variables is eliminated? multiply the second equation by â’4 to get â’16x â’ 4y = â’80 multiply the second equation by â’1 to get â’4x â’ y = â’20 multiply the first equation by 2 to get 4x + 8y = 28 multiply the first equation by â’1 to get â’2x â’ 4y = â’14

The water aquarium shark tank is always greater than 25 feet of the water level decreased by 6 feet during cleaning what was the water level before the cleaners took out any water