If quick copy recently charged 49 cents per page for color copies and 9 cents per page for back and white copies. if shirlees bill for 90 copies is $12.90, how many copies of each type were made? it needs to be written like in algebra let x= or x+y something like that

What is f(3) for the quadratic function f(x)= 2x^2+ + x - 12

(a) calculate the molarity of a solution that contains 0.0345 mol nh4cl in 400 ml of solution. (b) how many moles of hno3 are present in 35.0 ml of a 2.20 m solution of nitric acid? (c) how many milliliters of 1.50 m koh solution are needed to supply 0.125 mil of koh ?

Express in the simplest form: (x^2+9x+14/x^2-49) / (3x+6/x^2+x-56)