Ah, so creating variables...
Imagine this question in a different way. The first day's total was the same as the second day's.
Then, since both days have the same totals, we can just assign a variable, x, for the total number of inches of rain.
So, x + x = 11.9
However, in this question, we have the first day's total as 5.4 inches less than the second day's total.
In this case, x = second day's total, so the first day's total is 5.4 - second day's total or 5.4 - x.
Now, instead of just x + x, we have (5.4 - x) + x...
That's cool, I have heard of Master Chief before!
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