Answer:
x=4.63
Step-by-step explanation:
Area = (1/2) (base) (height)
20 = (1/2) (x+4) (x)
40 = x²+4x
x²+4x-40=0
Put in quadratic equation:
x=
x=
x=4.63324958071 or x=-8.63324958071
Since x can't be negative in this case we take our answer to be 4.63324958071, which rounds to 4.63