To Simplify Fractions what you have to do is get the number then see what can divide into both the numerator and denominator equally Here:
1.5/8 Nothing can go into both so you leave it.
2. 3/5 + 1/4 = 4/9 Still nothing can go into it.
3. 4/7 + 1/8 = 5/15 you can divide, 5 can go into 5 , 1 time , 5 can go into 15 3 times the answer is 1/3