First, for adding, subtracting, and comparing fractions, it is good to adjust both fractions to a common denominator. The common denominator you can calculate as the least common multiple of both denominators = LCM ⇒ (2, 4) = 4. We should do = three halfs + three quarters = nine quarters. Thus, 2 1/4 or 2.25 is the answer.
1 1/2 + 3/4 = 9/8 = 2 1/4 or 2.25
Feel free to rephrase this in your own words! Hope this helps!