Answer:
B. 10
Step-by-step explanation:
To find the answer we would plug each given number into x to see if it makes the equation true
A. 2(5) = 20
10 [tex]\neq[/tex] 20
B. 2(10) = 20
20 = 20
C. 2(20) = 20
40 [tex]\neq[/tex]20
As you can see, the only answer that makes the equation 2x=20 true, is answer B