Omar’s tank is 3/10 full. After he buys 11 gallons of gas, it is 4/5 full. How many gallons can Omar’s tank hold?

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?