Answer :
1. The numerical is too complicated for the students to solve.
To rewrite the sentences using the "too... to" pattern, follow these transformations:
The numerical is very complicated; the students cannot solve it.
Rewritten: The numerical is too complicated for the students to solve.The bag is very heavy; the girl cannot carry it upstairs.
Rewritten: The bag is too heavy for the girl to carry upstairs.The lady was very soft spoken; the audience could not hear her clearly.
Rewritten: The lady was too soft spoken for the audience to hear her clearly.Tom Sawyer was very naughty; Aunt Polly could not control him.
Rewritten: Tom Sawyer was too naughty for Aunt Polly to control him.The slope was steep; the old lady could not climb it.
Rewritten: The slope was too steep for the old lady to climb.