I need help with number 1 and 2

The price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?

1c) the number 131 is a term in the sequence defined by the explicit rule f(n)=5n-4. which term in the sequence is 131? 2a) write the first four terms of the function f(n)=n^2-1 2b) what is the 10th term of the sequence defined by the explicit rule f(n)=n^2-1 2c) the number 224 is a term in the sequence defined by the explicit rule f(n)=n^2-1. which term in the sequence is 224?

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?