You will be given a definition of a task first, then some input of the task.
In this task, you need to provide the correct option for a given problem from the provided options.

Problem: the ratio of red balls to blue balls is 3 : 7 . 70 % of the red balls and 30 % of the blue balls are tennis balls . how many of the balls are tennis balls ?
Options: a ) 44 % , b ) 40 % , c ) 45 % , d ) 42 % , e ) 48 %
Output:
d