Answer:
6
Explanation:
Let's call the number of red cubes that Sam has r, and the number of yellow cubes that she has y.
Since the sum of the number of cubes is 20:
r+y=20
Since she has 8 more yellow cubes than red ones:
y=r+8
You can now plug this back into the first equation:
r+(r+8)=20
2r+8=20
2r=12
r=6
Therefore, Sam has 6 red cubes. Hope this helps!
Hope this helps!