Answer:
3/8 of the box
Explanation:
On Friday Merinda uses 1/4 of the box of pancake mix to make pancakes.
On Saturday she uses 1 1/2 times as much pancake mix as Friday.
On Friday = 1/4 of the box
On Saturday = 1 1/2 × pancake mix as Friday
Hence, 3/8 of the box of pancake mix does Merinda use on Saturday.