Chords ab and cd intersect at point e, ae = 10, eb = 4, and ce = 8. therefore, ed =

So here is how we are going to find out what is ED. 
Based on the given figure, it states that AE is 10, and EB is 4 and CE are 8.
So, (AE/CE)=(ED/EB)
10/8 = ED/4 <<multiply both sides by the common denominator which is 8 and the result would be:
80/8 = 8ED/4
10 = 2ED <<divide both sides by 2 and we get
ED = 5.
Therefore, the measurement of ED is 5. 

C+19÷-17=17c+(-1.11764706)=17c=.11764706)c=18.1176471