First add up all the amount of smoothie ingredients you use
1 1/3 + 1/2 + 1 + 3/4
because they're all in cups you can add them together without converting but you have to change the denominator to add the fractions together
1 2/6 + 3/6 +1 +3/4 =
1 5/6 + 1 + 3/4
1 10/12 + 9/12 + 1 =
1 19/12 + 1
2 7/12 +1 = 3 7/12
and because 3 7/12 means 3 cups and 7/12 of a cup she doesn't have enough cups for her and 3 of her friends because she'd need at least 4 cups. In order for her to have enough for all her friends she would need to add 5/12 of one of the ingredients to get 4 cups.
2.
3 7/12 - 3/4 × 4
= 3 7/12 - 12/4
= 3 7/12 - 3
= 7/12
so she would have 7/12 cups left over
