Atriangular banner has an area of 315 in^2

I added a screenshot with the complete question.

area of larger triangle = 560 in²

Explanation:
We are given that the ratio between the side length of the larger triangle to the smaller one is 4:3
We can use this information to get the ratio between their areas.
To get the ratio between the areas, we will simply square the ratio between the side lengths as follows:
                    area of large triangle : area of small triangle
                                 (4)²                :            (3)²
                                 16                  :             9

We are given that the area of the small triangle is 315 in², therefore, we can use cross multiplication to get the area of the large triangle as follows:
                   area of large triangle : area of small triangle
                                 16                :            9
                                  ??               :            315
area of large triangle = (315*16) / 9
area of large triangle = 560 in²

Hope this helps :)

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