Please help asap what vaule of x makes the equation true 3(x-4)=15

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

Bob is putting books on a shelf and takes a break after filling 18 1/2 inches on the book shelf. the book shelf is now 2/3 full. how long is the entire bookshelf?

Ok a point t on a segment with endpoints d(1, 4) and f(7, 1) partitions the segment in a 2: 1 ratio. find t. you must show all work to receive credit.