What you want to do is find the greatest common denominator, so for now put the 17 to the side and focus on the 1/4 and 7/8, we can find the GCD (greatest common denominator) by multiplying 1/4 • 8/8 = 8/32 And then multiplying 7/8 • 4/4 = 28/ 32 So here we have remaining 17 & 8/32 cups PLUS 28/32 cups, you can add the numerators straight across and keeps the denominators the same, which says that she uses 18 & 4/32
Simplified version: 18 & 1/8