In June, Mr. Chen's students read 40 books. In July they read 30 books. What is the percent increase or decrease of the books they read?

Can someone me and do the problem plz so i can understand it more better

Juliana says that she can use the patterns of equivalent ratios in the multiplication table below to write an infinite number of ratios that are equivalent to 6: 10. which statement explains whether juliana is correct? she is correct because she can multiply 6 and 10 by any number to form an equivalent ratio. she is correct because 6: 10 can be written as 1: 2 and there are an infinite number of ratios for 1: 2. she is not correct because the multiplication table does not include multiples of 10. she is not correct because 6: 10 is equivalent to 3: 5 and there are only 9 ratios in the multiplication table that are equivalent to 3: 5.

What is the effect on the graph of the function f(x)=x when f(x) is replaced with -f(x)+4