Can someone explain why in this question do we do the Total income for the company - The total cost to the company? I will give brainliest, if that's how it's spelt.

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.

Need the graph to answer this.