if a and b are positive integers, and a = 5 b + 20, the greatest common divisor of a and b can not be Pick one:
A) 2	B) 4	C) 5	D) 6	E) 10
<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 + 2</gadget>
<output>6</output>

<result>D</result>
if a and b are positive integers, and a = 5 b + 20, the greatest common divisor of a and b can not be
add(divide(20, 5), const_2)
if b is 2 , 4 , 5 , or 10 , then gcd of a and b is 2 , 4 , 5 , and 10 respectively . so , by poe the answer must be d . still : if b is a multiple of 6 , then a is 20 greater than a multiple of 6 , so not a multiple of 6 , so both of them can not be divisive by 6 . answer : d .