Answer:
Area =100 in^2
Explanation:
scale factor of the triangles is :15/21=5/7
if two similar shape has a scale factor a/b then the area is a^2:b^2
area of first shape/area of second shape=5/7
x/196=(5)²/(7)²
49x=4900
x=4900/49=100
area=100
check: 100/196=25/49=a^2/b^2
i hope it is right