In this case, we have a 6×7 rectangle. We can express the 7 as 3 + 4 (3 + 4 = 7) and then write the 6×7 dimensions of the figure like this:
6×7 = 6×(3 + 4)
By applying the distributive property:
6×(3 + 4) = 6×3 + 6×4 = (6×3) + (6×4)
Then, option C is the correct answer.