how many pollen grains are formed in 10 flowers of brinjal if each microsporangium has 10 pollen mother cells?

Brinjal is dithecous having two lobes and each lobe has two microsporangia. So one flower has 4 microsporangia.

Each Microsporangia has 10 pollen mother cells so total 40 pollen mother cells in one flower. 10 flowers of brinjal will have in total 400 pollen mother cells. Each pollen mother cell produces 4 pollen grains so 400 will produce= 4*400= 1600 pollen grains.