Point G lies between points F and H on Line segment F H. A line contains points F, G, H. The space between F and G is 4 x. The space between G and H is 2 x. If the length of FH is 18 units, what is the value of x?

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.