Question 1170584
Let t be the number of 20 peso bills, and f the number of 50 peso bills.
t+f=25
20t+50f=950

Using system of equations we can find our answer. Multiply the first equation by 20 to get 20t+20f=500. Then, subtract the two equations to get rid of t.

This now turns into: 30f=450
Divide both sides by 30 to get f=15

Plug f into the first equation to get a value of 10 for t.
There are 10 20 peso bills, and 15 50 peso bills.


CHECK
t+f=25
10+15=25
TRUE
20t+50f=950
20*10+50*15=950
200+750=950
TRUE