Answer:
Cassie will have 40 marbles.
Step-by-step explanation:
Cassie has 8 red marbles and 12 yellow marbles.
Her mom doubles her red and yellow marbles for her birthday.
So, we can denote this mathematically as:
2(8) for red marbles.
2(12) for yellow marbles.
We can write total marbles as:
\(2(8)+2(12)\) or
\((8+12)\times2\)
= \((20)\times2\)
Total marbles = 40
