a) 186 - 3 x y = 99
3 x y = 186 - 99
3 x y = 87
y = 87/3
b) y :2 + y:3 + y:4 = 15
y x 1/2 + y x 1/3 + y x 1/4 = 15
y x ( 1/2 + 1/3 + 1/4) =15
y x 13/12 = 15
y = 15 : 13/12
y = 180/13
Tìm y biết
a 186 -3 x y = 99
3 x y = 186 - 99
3 x y = 87
y = 87 : 3
y = 29
b y :2 + y : 3 + y : 4 = 15
\(\frac{y}{2}+\frac{y}{3}+\frac{y}{4}=15\)
\(\frac{6\times y}{12}+\frac{4\times y}{12}+\frac{3\times y}{12}=\frac{180}{12}\)
\(6\times y+4\times y+3\times y=180\)
\(\left(6+4+3\right)\times y=180\)
\(13\times y=180\)
\(y=180:13\)
\(y=\frac{180}{13}\)
MÌNH GHI RA TỪNG CHI TIẾT RỒI NHA , CHÚC BẠN HỌC TỐT !!!
a,186-3xy=99
3xy=186-99
3xy=87
y=87:3
y=29
a) 186 - 3y = 99
\(\Rightarrow\)3y = 186 - 99
\(\Rightarrow\)3y = 87
\(\Rightarrow\)y = 87 : 3
\(\Rightarrow\)y = 29
vậy y = 29
b) \(\frac{y}{2}+\frac{y}{3}+\frac{y}{4}=15\)
\(\Rightarrow\frac{6y}{12}+\frac{4y}{12}+\frac{3y}{12}=\frac{180}{12}\)
\(\Rightarrow6y+4y+3y=180\)
\(\Rightarrow y\left(6+4+3\right)=180\)
\(\Rightarrow y13=180\)
\(\Rightarrow y=180:13=\frac{180}{13}\)
vậy y = 180/13