Under her cell phone plan, Alexa pays a flat cost of $39.50 per month and $4 per gigabyte. She wants to keep her bill at $53.10 per month. Which equation could be
used to determine g, the number of gigabytes of data Alexa can use while staying
within her budget?

g=53.1-39.5/ 4
4g = 39.5 – 53.1
39.5g + 4 = 53.1
4(39.5+ g) = 53.1

Someone help pls