Sean sold half of his comics to buy a game. Later, he bought 7 new comics. How many did he start with if he now has 20:

That’d be 9 years or something

This is what i found “an explicit formula designates the nth term of the sequence, as an expression of n (where n = the term's location). it defines the sequence as a formula in terms of n. this example is an arithmetic sequence(the same number, 5, is added to each term to get to the next term).” i hope this you for what your looking for. can you plz mark me brainliest?