Xin CTLHN
Câu 1
a,$\frac{5}{11}$+$\frac{6}{7}$+$\frac{6}{11}$+$\frac{1}{7}$
=($\frac{5}{11}$+$\frac{6}{11}$)+($\frac{6}{7}$+$\frac{1}{7}$)
=$\frac{11}{11}$+$\frac{7}{7}$
=1+1
=2
b,y+y:0,5+y:0,25+y:0,125=45
⇒y+y:$\frac{1}{2}$+y:$\frac{1}{4}$+y:$\frac{1}{8}$=45
⇒y+y×2+y×4+y×8=45
⇒y×(1+2+4+8)=45
⇒y×15=45
⇒y=45:15
⇒y=3
Vậy y=3