Question: Fill in the missing digits in the sum.

Predict: I thought this would be about addition.

Clarify: I had nothing to clarify.

Find the big picture: What are the missing numbers?

Solve:

First I worked out that 7+6 is 13, and 13+2 is 15, so I put a 2 in the box and carried the one.

Next I worked out that 1+3+1 is 5, and 5+4 is 9, so I put the 4 in the next box.

Summary: I used my prior knowledge.