Answer:
80 1/2 days between first and second son
This in days is 1-81 days to finish one house.
Explanation:
1st Son = 45 + 18 + 27 = 90 saved the father 18 days. 27 of 45 = 60% inv 40%
2nd Son = 45 + 9 +36 = 90 saved the father 9 days = 36 of 45 = 80% inv 20%
1st Son 40% needs to be increased 60% to complete house
2nd Son 20% needs to be increased 80% to complete house
1st Son House takes Son 1 in days = 27 x 1.60% = 43.2 + 27 = 60.2
2nd Son House takes Son 2 in days = 36 x 1.80%= 64.8 + 36 = 100.8
60.2+100.8 = 161 days.
=161 days for 2 homes.
= 80 1/2 days for one home.