Answer:
Helen requires 15$ more to buy the three books.
Step-by-step explanation:
We are given the following in the question:
Cost of dictionary = $7
Cost of dinosaur book = $16
Cost of cook book = $17
Helen's allowance = $25
Total cost of three books =
[tex]=7 +16+17\\=\$ 40[/tex]
Extra money required to buy three books =
[tex]=40-25\\=\$15[/tex]
Thus, Helen requires 15$ more to buy the three books.