Question

Si el 25% del 30% del 40% de a es 9, y el 50% del 20% del 70% de a es b. hallar : (b-1)% de 30 mas el (b+9)% del 40% de 1000

Answer 1

$\frac{25}{100} * \frac{30}{100}* \frac{40}{100}*a= 9 \\ \\ \frac{1}{4}* \frac{3}{10}* \frac{2}{5}*a =9 \\ \\ \frac{3}{100} *a =9 \\ \\ 3a=900 \\ \\ a=300$

$\frac{50}{100}* \frac{20}{100}* \frac{70}{100} *a= b \\ \\ \frac{1}{2}* \frac{1}{5}* \frac{7}{10} *300= b \\ \\ \frac{1}{10}* \frac{7}{10} *300= b \\ \\ 21= b$

(b-1)%= 21-1=20%
100% ⇒30
20% ⇒ x
$\frac{20*30}{100} = 6$

(b+9)= 21+9=30%
$\frac{30}{100} * \frac{40}{100} *1000 \\ \\ \frac{3}{10} * \frac{2}{5} *1000 \\ \\ 6(20)= 120$