The right answer is 202.5 - 292.5 grams of carbohydrates a day.
The man's caloric requirements are around 2500 calories / day. So the subject tries to create a calorie deficit.
1 gram of carbohydrate equals 4 calories.
45% - 65% of the calorie intake (1800kcal) corresponds to 0.810 - 1.170 Kcal. (810 and 1170 calories).
So:
4 calories ==> 1 gram of carbohydrates
810 calories ==> 810/4 = 202.5 grams of carbohydrates
1170 calories ==> 1170/4 = 292.5 grams of carbohydrates.
So, the subject must consume between 202.5 and 292.5 grams of carbohydrates a day.