a, 75 x x = 1800              x = 1800 : 75             x = 24 c, x x 405 = 86265         x        = 86265 : 405        x        = 213      Đây nha em.

a, 75 x X = 1800

              x= 1800:75

               x= 24

b,   1855:X = 35

                x=1855:35

               x =53

50+45=95,50/45+45/50=1

505 + 505 = 1010

50/45 + 45/50=2.01111111111 

\(42+42+45+45\)

\(=2.42+2.45\)

\(=2.\left(42+45\right)\)

\(=2.87\)

\(=174\)

42 + 42 + 45 + 45 

= 42 x 2 + 45 x 2 

= 84 + 90 

= 174

B.3 405 759

c bạn nhé

C

450:27

ket qua bang 3 nhe

17/45+23/45+28/45+1/27+26/27+22/45

=(17/45+23/45+28/45+22/45)+(1/27+26/27)

=2+1

=3

\(\frac{45x16-17}{45x15-28}\)\(=\frac{703}{647}\)

Tích tớ nha

ai truoc minh cho

a) \(\frac{2}{5}+\frac{9}{15}=\frac{2}{5}+\frac{3}{5}=\frac{5}{5}=1\)

b) \(\frac{15}{45}+\frac{25}{30}=\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{7}{6}\)

c) \(\frac{28}{32}+\frac{45}{72}=\frac{7}{8}+\frac{5}{8}=\frac{12}{8}=\frac{3}{2}\)

d) \(\frac{8}{28}+\frac{5}{30}=\frac{2}{7}+\frac{1}{6}=\frac{12}{42}+\frac{7}{42}=\frac{19}{42}\)

a) \(\frac{2}{5}+\frac{9}{15}\)=\(\frac{2}{5}+\frac{3}{5}=\frac{2+3}{5}=1\)

b)\(\frac{15}{45}+\frac{25}{30}=\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{2+5}{6}=\frac{7}{6}\)

c)\(\frac{28}{32}+\frac{45}{72}=\frac{7}{8}+\frac{5}{8}=\frac{7+5}{8}=\frac{12}{8}=\frac{3}{2}\)

d)\(\frac{8}{28}+\frac{5}{30}=\frac{2}{7}+\frac{1}{6}=\frac{12}{42}+\frac{7}{42}=\frac{12+7}{42}=\frac{19}{42}\)

\(=\frac{20}{45}+\frac{32}{3}.45\)

\(=\frac{20}{45}+480\)

\(=\frac{4324}{9}\)

tíc mình nha

20/45+(2/3+10).45

=4/9+16/5.45

=4/9+144

=1300/9