math
posted by jason .
A pencil, eraser, and notebook cost $1 in total. A notebook costs more than 2 pencils, 3 pencils cost more than 4 erasers, and 3 erasers cost more than a notebook. How much does each item cost?

Pencil costs $0.26.
Eraser costs $0.19.
Notebook costs $0.55.
Solution of Diophantic equation
p + e + n = 100
with constraints
n > 2 p
3 p > 4 e
3 e > n 
Sophia spent $7.30 for school supplies. She spent $3.00 for a notebook and $1.75 for a pen. She also bought 3 large erasers. If each eraser had the same cost, how much did she spend for each eraser?