Height=15
Explanation:
Area of a triangle= 1/2base x height
Plug in information
30=1/2 x 4 x h
Solve 1/2 x 4 = 2
30= 2 x h
Divide both side by two
30/2=2 x h/2
Solve:
15= h
Area of triangle is
A=b•h/2
A=(10x+5)(2x-5)/2
A=20x^2-50x+10x-25/2
A=20x^2-40x-25/2
A=2(10x^2-20x-12.5)/2
cancel 2 in numerator and denominator
A=10x^2-20x-12.5 in^2
Hope this helps
Answer is in the photo w step by step

Let's solve ~




Therefore, Option D is correct ~