a) 3y + 2y = 850

5y = 850

y = 850 : 5

y = 170

Ps: Ko nên tự trả lời ,tự !

a)3y+2y=850

5y=850

y=850/5

y=170

b, (y+1) + (y+2) + (y+3) + .... + (y+99) = 6138

(y+y+y+y+....+y) + (1+2+3+...+99) = 6138

99.y + 4950 = 6138

99.y = 6138 - 4950

99.y = 1188

y = 1188 : 99

x = 12

a) \(\left(y+1\right)+\left(y+4\right)+\left(y+7\right)+....+\left(y+28\right)=155155\)

\(\Rightarrow\left(y+y+...+y\right)+\left(1+4+7+...+28\right)=155155\)

\(\Rightarrow10x+145=155155\)

\(\Rightarrow10x=155010\)

\(\Rightarrow x=15501\)

Vậy x = 15501

b) \(\left(y+1\right)+\left(y+2\right)+..+\left(y+99\right)=6138\)

\(\Rightarrow\left(y+y+...+y\right)+\left(1+2+3+...+99\right)=6138\)

\(\Rightarrow99x+4950=6138\)

\(\Rightarrow99x=1188\)

\(\Rightarrow x=12\)

Vậy x = 12

\(6xy+\left(\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{7x8}\right)=\frac{29}{8}\)

Đăt \(A=\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{7x8}\)

\(\Rightarrow A=\frac{3-2}{2x3}+\frac{4-3}{3x4}+\frac{5-4}{4x5}+...+\frac{8-7}{7x8}\)

\(A=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{7}-\frac{1}{8}=\frac{1}{2}-\frac{1}{8}=\frac{3}{8}\)

\(\Rightarrow6xy+A=6xy+\frac{3}{8}=\frac{29}{8}\Rightarrow6xy=\frac{26}{8}\Rightarrow y=\frac{26}{8x6}\)

các bạn trả lời giúp mình trước 12 giờ nhé.Mong oline math trả lời giúp mình

a)\(100\%\times y-40\%\times y=3,6\\ 60\%\times y=3,6\\ y=6\)

b)Gợi ý :\(75\%=\frac{3}{4}\)

c) và d)Gợi ý :\(y-108,34-45,99=168,04\\ y-108,34=168,04+45,99=214,03\)

câu a để sau

b) x = 3; y = 5

y x 6 + y x 3 + y = 80

y x 6 + y x 3 + y x 1 = 80

y x (6 + 3+ 1) = 80

y x (9 + 1) = 80

y x 10 = 80

y = 80 : 10

y = 8

y x 6 + y x 3 + y x 1 = 80

y x ( 6 + 3 + 1 ) = 80

y x ( 9 + 1 ) = 80

y x 10 = 80

y = 80 : 10

y = 8

\(96-\left(37,5:y\right)=94,5\)

\(37,5:y=1,5\)

\(y=25\)

\(\frac{6}{13}:\left(\frac{1}{2}+y\right)=\frac{15}{39}\)

\(\frac{1}{2}+y=\frac{6}{5}\)

\(y=\frac{7}{10}\)

đấy là y phần 2, 3 ạ

a, x=3 thì y=5

x=5 thì y=3

b,x=3 thì y=3

số đó là

b và a

đầu bằng

3 nhé bn

3y + 1/2y + 1/4y = \(1\frac{1}{2}\)

15/4y = \(1\frac{1}{2}\)

y = \(1\frac{1}{2}:\frac{15}{4}=\frac{3}{2}:\frac{15}{4}=\frac{2}{5}\)