An easy way to understand this is to think of it as quarters (like the money). A quarter is $0.25 and it takes 4 quarters to equal one dollar ($1.00). This being said, 1 quarter would be 1/4 of a dollar (0.25), 2 quarters would be 2/4 of a dollar (or 1/2 if you simplify it) (0.50), 3 quarters would be 3/4 of a dollar (0.75), and 4 quarters would be 4/4 (or 1 when you simplify it) of a dollar. You can convert this into decimals by making it 2 - 1.25 which would equal 0.75 (3/4).
Hope this helps!