Answer:
3x + 10cm
Step-by-step explanation:
This is calculated as:
Length of Tom's pencil - Length is Ellen's pencil
Length of Tom's pencil: 5x+25cm long.
Length of Ellen's pencil : 2x+15cm long.
(5x + 25)cm - (2x + 15)cm
5x + 25 - 2x - 15
5x - 2x + 25 - 15
3x + 10 cm
Therefore, Tom's pencil is 3x + 10cm longer is than Ellen's.
