What's the function notation for this? And which one is the independent and dependent variable?

Which equation can be used to solve for the unknown number? seven less than a number is thirteen. n-7=13 7-n=13 n+7=13 n+13=7

Which of the following is the rational exponent expression of 6 root f

You invested $5000 between two accounts paying 4% and 9% annual interest, respectively. if the total interest earned for theyear was $350, how much was invested at each rate? $was invested at 4% andwas invested at 9%.