a) a+a+a+a = 4a
b) [tex] \frac{3}{4} + \frac{b}{4} = \frac{3 + b}{4} [/tex]
c) [tex] \frac{k}{7} + \frac{5}{7} = \frac{k + 5}{7} [/tex]
ç) [tex] \frac{1}{7} .m = \frac{m}{7} [/tex]
d) [tex] \frac{a}{4} - 3 = \frac{a - 12}{4} [/tex]
