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There is a similar worksheet here on adding three numbers within 20 (although not always with two of them adding up to 10.) There is also another similar adding three numbers worksheet with numbers to 100.

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The various resources listed below are aligned to the same standard, (1OA06) taken from the CCSM (Common Core Standards For Mathematics) as the Addition and subtraction Worksheet shown above.
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13  4 = 13  3  1 = 10  1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12  8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).