Answer:
Step-by-step explanation:
First you have to calculate CB in order to use sin law to calculate ∠A
CB=
CB=12.8(correct to nearest tenth)
After that, use sin law to calculate ∠A,
or 
sinA=0.695...
A=44.079...
=44.1(corrext to the nearest tenth)
Is that clear enough for you?
When two lines cross like this, sum of measures of opposite angles is 180.
this means that:
measure angle AEC + measure angle BED = 180
4x-40 + x+50 = 180
5x +10 = 180
5x = 170
x = 34
therefore:
measure angle AEC = 4x-40 = 4(34)-40 = 96
measure angle BED = x+50 = 34+50 = 84
The greatest common factor is 2b
