Answer:To estimate the sum of 45,670 and 34,115 to the nearest thousand: 1. Round each number to the nearest thousand:- 45,670 rounds to 46,000- 34,115 rounds to 34,0002. Add the rounded numbers:- 46,000 + 34,000 = 80,000 Therefore, the estimated sum of 45,670 + 34,115 to the nearest thousand is 80,000.