Answer = 1.414
I used the prime factorization method.
Hope this answers your question.
If you mean 2x=40 x=20
but if you mean x^2=40 i think its x=80
Answer:

Step-by-step explanation:
1. Combine like terms
2y-7y = -5y
-5y=5
2. Divide by -5 and the answer is 
X=12sin(60). X=10.3923...X=6rad3
CDAB
4.2 (convert to frac on ur own)
12.5=x
CB= 14.5
AB= 8.82