Five less than the product of 21 and a number

When y’all answer can y’all explain too !

Beth divided 9 ounces of her granola recipe into 4 equal-sized amounts. she placed the amounts into individual bowls. the fraction 9/4 represents the number of ounces of granola in each bowl. which other number represents the amount of granola beth has in each bowl? (a) 1 1/4 (b) 2 1/4 (c) 1 3/4 (d) 3 3/4 i need !

Determine if the equation defines y as a function of x: 2xy = 1. yes o no