Answer:
2 3/4 C
Step-by-step explanation:
[tex](21+\frac{1}{4})-(18+\frac{2}{4})\\=21-18+\frac{1}{4} -\frac{2}{4} \\=3-\frac{1}{4} \\=\frac{12-1}{4} \\=\frac{11}{4} \\=2\frac{3}{4} \\or\\21\frac{1}{4} -18\frac{2}{4} \\=\frac{85}{4} -\frac{74}{4} \\=\frac{85-74}{4} \\=\frac{11}{4} \\=2\frac{3}{4}[/tex]