Contrast the relative positions of the sun, earth, and the moon during the full moon phase and new moon phase.

During full moon phase Moon, Earth and Sun agreed with the Earth dividing the Moon and the Sun. However, normally the arrangement isn't flawless with the Moon's longitude lying somewhat above or beneath the Sun's longitude. The Earth-Moon line and the Earth-Sun line are near 180 degree away which is known as Lunar Eclipse, when the Moon passes directly bellow Earth and steps into its shadow. Then during new moon phase Earth, Moon and Sun agreed with the Moon separating the Earth and the Sun. The Earth-Moon line and the Earth-Sun line are near zero degree. Neverthless sometimes the arrangement could be close ideal prompting an overshadowing of Sun by the Moon which is known as solar eclipse

Amath expression is a collection of one or more terms, which are separated by the signs ( + , - , x , / ).example :   8+b8+b  or  a−3a−3in algebra, an equation is a mathematical statement with two expressions where, each expression is separated by an equal (=) sign. variables can be present on both the sides of the equality (=) sign and we use letters to denote such variables.example 1:   x=4+2x=4+2  , [here, we can observe that the variable is present only on one side of the equation].example 2:   2x+3=x+42x+3=x+4  , [here, we can observe that the variables are present on both side of the equation].