5/4 - 3/4 this is used with fractions with mixed numbers. (infinite pre algebra) me

Solve with work adding cheese to a mcdonalds quarter pounder increases the fat content from 21g to 30g. what is the percent of change ?

Cora bought a package of erasers. there are 4 pink erasers and 12 blue erasers. what is the ratio of pink erasers to blue erasers?

Afarmer has a large field that is x feet in length. he wants to fence in a rectangular section in the middle of the field , leaving a length of 100 feet of open field behind each end of the fenced rectangle.he also wants the width of the fenced-in space to be 100 feet less than its length. find the expressions to represent the length and width of the fenced section of the field