What is the percent of decrease from 100 to 57?

Pls! does anybody know a shortcut for answering these types of questions in the future?

Let x = a + bi and y = c + di and z = f + gi. which statements are true?

Pranav and molly are selling pies for a school fundraiser. customers can buy blueberry pies and pumpkin pies. pranav sold 6 blueberry pies and 4 pumpkin pies for a total of $106. molly sold 6 blueberry pies and 3 pumpkin pies for a total of $90. find the cost of each of one blueberry pie and one pumpkin pie