Odpowiedź :
a)
[tex]1\dfrac{2}{7}+\dfrac{1}{4}=1\dfrac{2\cdot4}{7\cdot4}+\dfrac{1\cdot7}{4\cdot7}=1\dfrac{8}{28}+\dfrac{7}{28}=\boxed{1\dfrac{15}{28}}\\[/tex]
b)
[tex]1\dfrac{3}{4}+3\dfrac{3}{5}=1\dfrac{3\cdot5}{4\cdot5}+3\dfrac{3\cdot4}{5\cdot4}=1\dfrac{15}{20}+3\dfrac{12}{20}=4\dfrac{27}{20}=\boxed{5\frac{7}{20}}\\[/tex]
c)
[tex]5\dfrac{2}{3}-3\dfrac{2}{5}=5\dfrac{2\cdot5}{3\cdot5}-3\dfrac{2\cdot3}{5\cdot3}=5\dfrac{10}{15}-3\dfrac{6}{15}=\boxed{2\frac{4}{15}}\\[/tex]
d)
[tex]7\dfrac{1}{8}-5\dfrac{3}{4}=7\dfrac{1}{8}-5\dfrac{3\cdot2}{4\cdot2}=7\dfrac{1}{8}-5\dfrac{6}{8}=6\dfrac{9}{8}-5\dfrac{6}{8}=\boxed{1\frac{3}{8}}\\[/tex]
Odpowiedź:
Sprowadzamy do wspólnego mianownika.
[tex]a) 1\frac{2}{7} +\frac{1}{4} =1\frac{8}{28} +\frac{7}{28} =1\frac{15}{28} \\ \\ b) 1\frac{3}{4} +3\frac{3}{5} =1\frac{15}{20} +3\frac{12}{20}=4\frac{27}{20} =5\frac{7}{20}\\ \\ c) 5\frac{2}{3}-3\frac{2}{5}=5\frac{10}{15}-3\frac{6}{15}= 2\frac{4}{15}\\ \\ d) 7\frac{1}{8} -5\frac{3}{4} =7\frac{4}{32} -5\frac{24}{32} =1\frac{12}{32} =1\frac{3}{8} [/tex]
Mam nadzieję, że pomogłam :)