6th grade math , please help

This is so harddd! solve. 1 + 1 = solve 4 + 4 = solve 3 x 3

The late fee for library books is $2.00 plus 15¢ each day for a book that is late. if maria’s fee for a late book was $3.20, write and solve a linear equation to find how many days late the book was.

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?