What two pieces of information would researchers need to have in order to calculate the rate of plate motion for seafloor spreading?

-distance from the rift and age of seafloor sample
-type of rock and distance from the rift
-age of the continent and depth of the water
-age of the seafloor sample and age of the continent

Distance from the rift and age of seafloor sample

Explanation:

The seafloor spreading occurs along the mid-oceanic ridges and here the new crust is formed and thus moves gradually away from the ridge. The spreading can be determined by the age of the rocks and the age of the seafloor and the type of the rock associated with the distance from the rift.

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].