Answer:
Heidi bought 128 grapes.
Explanation:
So Heidi bought an unknown number of grapes. There are four days between Monday and Friday. You have to multiply 8 by 2 for every day that passed. 8 times 2 is 16. 16 times 2 is 32. 32 times 2 is 64. 64 times 2 is 128. So your answer will be 128 grapes.