Question

Aflati x stiind ca :
a) 10% din x este 40
b) 25% din x este 900
c) 80% din x este 1040
d) 24% din 240 este x
e) 15% din 300 este x ​

Answer 1

$10\%\:din\:x\:este\:40 \implies\frac{10}{100} \cdot x =40$

$\implies \frac{1}{10} \cdot x = 40 \,|\cdot10 \implies x= 10\cdot40=400$

$25\% \:din\: x \: este \: 900 \implies \frac{25}{100}^{(25} \cdot x =900$

$\implies \frac{1}{4} \cdot x = 900 \,|\cdot 4 \implies x=3600$

$80\%\:din\:x\:este\:1040 \implies \frac{80}{100} ^{(10}\cdot x = 1040$

$\implies \frac{8}{10} \cdot x=1040\,|\cdot10 \implies x=\frac{10400}{8} =1300$

$24\%\:din\:240\:este\:x \implies \frac{24}{100} \cdot240=x$

$\implies \frac{24\cdot240}{100} ^{(10}=x \implies x=\frac{24\cdot24}{10} =\frac{576}{10} =57,6$

$15\%\:din\:300\:este\:x \implies \frac{15}{100} \cdot 300 =x$

$\implies \frac{15\cdot300}{100} ^{(100}=x \implies x=15\cdot3=45$

Answer 2

a) 10/100 *x=40

   10x=40*100=4000

  x=4000/10=400

b) 25/100 *x=900

   25x=900*100

   25x=90000

    x=90000/25=3600

c) 80/100 *x=1040

   80x=1040*100

   80x=104000

   x=104000/80=1300

d) 24/100 *240=x

   24*240/100=x

   5760/100=x=57,6

e) 15/100 *300=x

   15*300/100=x

   15*3=x=45