If x + y ≥ a, x – y ≤ -1, and the minimum value of z = x + ay = 7, what is a?

Mp model with mathematics explain how the number of text messages dario sent and the cost form an arithmetic sequence. then write an expression to find dario's text messaging bill if he sends n text messages over 250.

Plz help plz give me the answer

Giuseppi's pizza had orders for $931.00 of pizzas. the prices were $21 for a large pizza, 514 for a medium pizza, and $7 for a small pizza. the number of large pizzas was two less than four times the number of medium pizzas. thenumber of small pizzas was three more than three times the number of medium pizzas. how many of each size of pizza were ordered?