উত্তর সিলেক্ট করলে সঠিক ও ভুল দেখাবে।
ব্যাখ্যা ও সঠিক সমাধান
উত্তর:
10
His son can wash the car in (15 × 2 = 30) minutes
Nazir can wash 1/15 part of the car in 1 minute
His son can wash 1/30 part of the can in 1 minute
Together they can wash (1/15 + 1/30 = 1/10) part of the car in 1 minute
So, together they can wash the whole car in 10 minutes.