Let x=number of 40c stamps, then 4x is the number of 25c stamps.
Total value of 40c stamps is 40x cents, and the total value of 25c stamps is 4x × 25c=100x cents.
So 40x+100x=2220 cents. x=2220/140=111/7 which is a mixed number=15⁶⁄₇.
Let’s assume x is 16, then there are 16 40c stamps and 64 25c stamps, totalling 6.40+16.00=P22.40.
If x=number of 25c stamps and 4x the number of 40c stamps total value is 0.25x+1.60x=1.85x=22.20, making x=12.
Perhaps this is the way the question is to be read, so there would be 12 25c stamps and 48 40c stamps, totalling 3.00+19.20=P22.20.