This is an assignment problem with decision variables defined as follows: x subscript i equals n u m b e r space o f space p l a n e s space o f space t y p e space i space s e n d space t o space C i t y space A y subscript i equals n u m b e r space o f space p l a n e s space o f space t y p e space i space s e n d space t o space C i t y space B The correct constraint for city B is: Group of answer choices 58 y subscript 1 plus 20 y subscript 2 plus 3.8 y subscript 3 greater or equal than 28 45 y subscript 1 plus 7 y subscript 2 plus 5 y subscript 3 greater or equal than 28 45 x subscript 1 plus 7 x subscript 2 plus 5 x subscript 3 greater or equal than 21 45 y subscript 1 plus 7 y subscript 2 plus 5 y subscript 3 greater than 28