Answer:
Marrisa didin't line up decimals correctly.
Step-by-step explanation:
We have been given that Marrisa added 1.56 and 13.47. She got 29.07. We are asked to find Marrisa's mistake.
Marrisa made a mistake, while writing 1.56 and 13.47 as a addition problem, We didn't place decimal correctly. She would have placed her digit as show below:
13.47
<u>+ 1.56 </u>
29.07
The correct answer would be:
13.47
<u>+ 1.56 </u>
15.03
Therefore, Marrisa didin't line up decimals correctly.