SAT math multiples question

[Jack]

How can we find the multiples of 4 between 278 and 679, inclusive?

[miranda]

This can be solved using arithmetic sequences. We know that the nth term of an arithmetic sequence is given by the following formula:
, where is the first term of the sequence (in our case is 280 since is the first multiple of 4 starting from 278) and d is the common difference of the progression (in our case the difference equals 4). The last term of the sequence is the number 676 which is the greater multiple of 4 less or equal than 679.
Therefore

[Jack]

Thanks miranda!