Abox of fruit has three times as many nectarines as grapefruit. together there are 36 pieces of fruit. how many pieces of each type of fruit are there? write an equation to repsent this problem

Let the amount of grapefruit by g.  The amount of nectarines, n, is 3g.

The total amount of fruit is g+n which is also g+3g=4g.  But there are 36, so 4g=36.  That means g=9.  That also means that n=27.

There are 9 grapefruits and 27 nectarines.