How do you find the lowest common denominator for 8/15 + 2/12?

Given f(x) = 10x + 4 and g(x) = 3x - 8, what is f(x) + g(x) ? - 7x - 4 - 13x + 4 - 7x + 4 - 13x - 4

Imagine a new pasture with grass growing on it. every day after the seeds have germinated, the number of blades of grass in the pasture triples. after 18 days, the entire pasture is completely covered in grass. how many days did it take for the pasture to be one-third covered in grass?

7. the area of the playing surface at the olympic stadium in beijing isof a hectare. what area will it occupy on a plan drawn to a scaleof 1: 500?