It's more relevant in a word problem, where you need to extract the condition from text and translate it into syntactical math notation so you can compute.
"John wants to have 7 pizzas. He has already made 3 pizzas. How many more pizzas does he need to make?"
Data: 7 pizzas needed. 3 pizzas made.
Unknown: X pizzas more to make
Condition: X+3=7
Or for geometry diagram problems (diagram geometry is word problems where the words are pictures), where you have to extract the relationships from the diagram.
Comments
Yes.
It's more relevant in a word problem, where you need to extract the condition from text and translate it into syntactical math notation so you can compute.
"John wants to have 7 pizzas. He has already made 3 pizzas. How many more pizzas does he need to make?"
Data: 7 pizzas needed. 3 pizzas made.
Unknown: X pizzas more to make
Condition: X+3=7
Or for geometry diagram problems (diagram geometry is word problems where the words are pictures), where you have to extract the relationships from the diagram.
The book has more examples.