104 subtracted from the quantity 6 times r is the same as r

104 subtracted from the quantity 6 times r is the same as r

The quantity 6 times r means we multiply 6 by r:
6r

104 subtracted from 6r is written as:
6r - 104

The phrase is the same as means we have an equation. So we set 6r - 104 equal to r
6r - 104 = r