There seems to be a problem with your question - AEC does not create a triangle while ADE does.
As for finding x
Draw an imaginary line from C to D. 3^2+4^2=5^2, so take the square root to find CD=5. Now we know that CA is also 5. To find x, x^2+3^2=5^2, or x^2+9=25. Subtract 9 from both sides to get 16, and take the square root of both sides to get x=4.
B. 4(4a+5)
4 would multiply all what’s in the bracket
16a +20
Answer: 3 hours
Step-by-step explanation: 65x4=260 455-260=195 195/65=3