Answer:
f + t = 19
5f + 20t = 305
Explanation:
"f" represents the number of $5 notes Jose has, and "t" represents the number of $20 notes Jose has. So, we can get our first equation f + t = 19 (the number of $5 notes + the number of $20 notes = total number of notes).
If you think about it, if you have "f" $5 notes, then the amount of money you have from those "f" amount of $5 notes will be 5 * f. As an example, if f = 3 (you have 3 $5 notes), you will have 5 * 3 = $15. This is the first part of the second equation. You follow the same logic for 20t, which tells you that you have "20t" dollars in total from your $20 bills.
Together, the total amount of money you have from your $5 notes (5f) plus the total amount of money you have from your $20 notes (20t) gives you $305.