PLEASE NEED HELP, don't understand it and been at it for hours given the equation for cos (a + b) determine what the cos(2a)=? *hint think of a way to represent 2a by adding*​

Volume of a cylinder with a radius of 13 in and height of 30 in

Beth divided 9 ounces of her granola recipe into 4 equal-sized amounts. she placed the amounts into individual bowls. the fraction 9/4 represents the number of ounces of granola in each bowl. which other number represents the amount of granola beth has in each bowl? (a) 1 1/4 (b) 2 1/4 (c) 1 3/4 (d) 3 3/4 i need !

Javier bought a painting for $150. each year, the painting's value increases by a factor of 1.15. which expression gives the painting's value after 77 years?