Question

tim x thuoc N

(7.13+8.13):(8+21-x)=39

Answer 1

(7.13+8.13):(8+21-x)=39

13(7+8):(29-x)=39

13.15:(29-x)=39

195:(29-x)=39

29-x=195:39

29-x=5

x=5+29

x=34

Answer 2

PT tương đương với:

\(\Leftrightarrow13\cdot\left(7+8\right):\left(29-x\right)=3\cdot13\)

\(\Leftrightarrow15:\left(29-x\right)=3\)

\(\Leftrightarrow29-x=15:3=5\)

\(\Leftrightarrow x=29-5=24.\)