Bobby has 3 times as many model spaceships as his friend sylvester does. bobby has 21 spaceships. how many model spaceships does sylvester have?

He has seven models because 21 divided by 3 is seven

Set the problem up like this:
3•X=21
then divide both sides by 3 and you get:
Sylvester has 7 spaceships

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?