Question

x+x*1/4:2/7+x:2/9=255

tính nhanh

 

Answer 1

Lời giải:

$x+x\times \frac{1}{4}: \frac{2}{7}+x: \frac{2}{9}=255$

$x+x\times \frac{7}{8}+x\times \frac{9}{2}=255$

$x\times (1+\frac{7}{8}+\frac{9}{2})=255$

$x\times \frac{51}{8}=255$

$x=255: \frac{51}{8}=40$