Respuesta :

x = some unknown number (think of it as a placeholder or a box for the number to go inside)

4x = the product of 4 and the unknown number

4x+19 = nineteen more than the product of 4 and a number

Answer: 4x+19

You may need to replace x with some other letter, so I would ask your teacher if they have a specific letter in mind (say n or something).