If the area of the triangle is 84 in2, what is the value of x?

I found the picture. It is shown that the length of the base is named x and the height is 7 in.

So, now you can use the formula of the area of the triangle:

area = base * height / 2

=> 84 in^2 = x * 7 / 2

And you can solve for x:

x = 2 * 84 in^2 / 7 in = 24 in

24 in

A,) cause a & b are equal & both gives 180°