Answer:
2/5
Step-by-step explanation:
add all marbles together: 10 marbles
since only 4 are red, the fraction would be 4/10
4/10 can be simplified to 2/5
3x+4=3*2+4
3*2+4=6+4
6+4=10
10=10
Enlargement? or try Translation
3/8
-3/2 can change to -12/8
7/4 can change to 14/8
1/8 stays the same
-12/8 + 14/8 = 2/8 + 1/8 = 3/8