Question

Norma bought 1 3/4 yards of cotton fabric and 3 3/8 yards of fleece fabric.

Answer 1

You need to first add the fractions not the mixed numbers. 1 3/4 + 3 3/8 = 5 1/8 simplified. So she bought 5 1/8 yards fabric.

Answer 2

1 3/4 + 3 3/8 
get a common denominator by multiplying 1 3/4 by 2 to get a denominator of 8
1 3/4 becomes 1 6/8
1 6/8 + 3 3/8 = 5 1/8 yards
so the answer is 
C. 5 1 / 8 Yards