It is greater than or equal to because she wants at least seven cm, which means that the length CAN be 7 cm, and it’s greater than because at least means a minimum of, so 7 cm or longer.
You add four because that’s how much hair she has already and you have 1.5x because that how much she growth per month. Plug in how many months for x and we’ll get a length in that amount of time
