3. Add or subtract:a. 4 -$\frac{5}{2}$ ...

a. 4 - $\frac{5}{2}$ = $\frac{4}{1}$ - $\frac{5}{2}$ = $\frac{8}{2}$ - $\frac{5}{2}$ = $\frac{3}{2}$
b. $\frac{3}{4}$ + 2 = $\frac{3}{4}$ + $\frac{2}{1}$ = $\frac{3}{4}$ + $\frac{8}{4}$ = $\frac{11}{4}$
c. 3 - $\frac{5}{6}$ = $\frac{3}{1}$ - $\frac{5}{6}$ = $\frac{18}{6}$ - $\frac{5}{6}$ = $\frac{13}{6}$
d. $\frac{8}{3}$ - 1 + $\frac{2}{5}$ = $\frac{8}{3}$ - $\frac{3}{3}$ + $\frac{2}{5}$ = $\frac{5}{3}$ + $\frac{2}{5}$ = $\frac{25}{15}$ + $\frac{6}{15}$ = $\frac{31}{15}$

Câu trả lời đầy đủ và chi tiết hơn:
a. 4 - $\frac{5}{2}$ = $\frac{4}{1}$ - $\frac{5}{2}$ = $\frac{8}{2}$ - $\frac{5}{2}$ = $\frac{3}{2}
b. $\frac{3}{4}$ + 2 = $\frac{3}{4}$ + $\frac{2}{1}$ = $\frac{3}{4}$ + $\frac{8}{4}$ = $\frac{11}{4}
c. 3 - $\frac{5}{6}$ = $\frac{3}{1}$ - $\frac{5}{6}$ = $\frac{18}{6}$ - $\frac{5}{6}$ = $\frac{13}{6}
d. $\frac{8}{3}$ - 1 + $\frac{2}{5}$ = $\frac{8}{3}$ - $\frac{3}{3}$ + $\frac{2}{5}$ = $\frac{5}{3}$ + $\frac{2}{5}$ = $\frac{25}{15}$ + $\frac{6}{15}$ = $\frac{31}{15}