Final answer:
To estimate the sum of 69.8 + 42.1 to the nearest ten, you round each number to the nearest ten and then add them, which gives you an estimated total of 110.
Step-by-step explanation:
To estimate the sum of 69.8 + 42.1 to the nearest ten, we look at the numbers to gauge their size rather than calculating the exact total. Estimating to the nearest ten involves looking at the ones place of each number. 69.8 is close to 70 and 42.1 is close to 40, so when we add these estimated values of 70 and 40, we get 110. Since 69.8 and 42.1 are both relatively close to their rounded values, 110 is a reasonable estimate of their sum to the nearest ten.