Answer :
To answer this question, you have to find the least common multiple of 5, 2, and 7.
1) Find the prime factorization of each of the numbers=5, 2, 7
2) Multiply the numbers: 5*2*7=70
3) Every 70 days he will do all three things on the same day
1) Find the prime factorization of each of the numbers=5, 2, 7
2) Multiply the numbers: 5*2*7=70
3) Every 70 days he will do all three things on the same day