Answer:
Step-by-step explanation:
since AD is a median it implies that triangle ABC is bisected to two equal right angled triangle which are ADB and ADC.
FE is parrallel to BC and cuts AB at F and AC at E shows that there are two similar triangles formed which are AFE and ABC.
Recall that ADC is a right angled triangle, ED bisects a right angled triangle the the ADE = .
Now, Let FD bisect angle ADB,
then ADF = too.
Since AFX is similar to Triangle ABD and that Triangle AEX is similar to Triangle ACD, then EDX is similar to FDX
FDE = ADF + ADE =
The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try! so im pretty sure its 20