Which problem situation can be represented by the algebraic model y=21 x a. alicia's car can travel 21 miles on one gallon of gas. how many miles, y, can it travel on x gallons? b. jeannie has read 21 pages of her book. how many pages, y, will she have read after reading x more pages? c. jeannie has read 21 pages of her book. how many pages, y, will she have read after reading x more pages? d. there were 21 students in mr. taylor's class. what is the number of groups, y he can have with x students in each group?