What is the area of an isosceles trapezoid if the lengths of its bases are 16 cm and 30 cm and the diagonals are perpendicular to each other?

How do you find the area of a triangle

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?

With alll of except for the 2 that i did already