The formula of area of trapezoid is given by
[tex]A = \frac{h (a+b)}{2}[/tex]
Where a and b are the two bases and h is the height and we have to solve for b .
TO solve for b, first we need to get rid of the denominator 2 by multiplying whole equation by 2, that is
[tex]2A = (a+b)h[/tex]
Now we need to get rid of h and for that we have to divide both sides by h, that is
[tex]\frac{2A}{h} = a+b[/tex]
Now we need to get rid of a by subtracting a to both sides.
[tex]b = \frac{2A}{h}-a[/tex]
Therefore correct option is D .
