The decimal expansion of 0.31717 is an infinite number with the 17 repeating.
Let the given decimal = X, so we have X = 0.31717 ( 1st equation)
Multiply both sides by 100 to get:
100x = 31.717 ( 2nd equation)
Subtract the 1st equation from the 2nd equation:
100x = 31.1717 - x = 0.31717 = 99x = 31.4
Divide both sides by 99:
X = 31.4 / 99
Multiply both numbers by 10 to remove the decimal point:
X = 314 / 990
Divide both numbers by 2 to get the final answer of 157 / 495
The answer is B.