The operation is defined for all integers a and b by the equation ab = (a - 1)(b - 1). If x20 = 190, what is the value of x ?	Choose one:
A) 10
B) 12
C) 11
D) 13
E) 14
ab = (a - 1)(b - 1)   x20 = (x-1)(20-1) = 190 --&gt; x-1=10 --&gt; x=11   Answer: 11
<result>C</result>
The operation is defined for all integers a and b by the equation ab = (a - 1)(b - 1). If x20 = 190, what is the value of x ?