Question

two variables X and Y varies directly with each other when X is 15 by 3 /

5 find X when Y is 18

Answer 1

$\textbf{Given:}$

$\text{x and y are varies directly}$

$\textbf{To find:}$

$\text{x when y=18}$

$\textbf{Solution:}$

$\text{Since x and y are varies directly, we can write}$

$y=k\,x$

$\text{when x=15 and y= \dfrac{3}{5} }$

$\dfrac{3}{5}=k(15)$

$\dfrac{1}{5}=k(5)$

$\implies\bf\,k=\dfrac{1}{25}$

$\therefore\boxed{\bf\,y=(\frac{1}{25})x}$

$\text{when y=18 }$

$18=(\frac{1}{25})x$

$\implies\boxed{\boxed{\bf\,x=450}}$

$\therefore\textbf{x is 450 when y=18}$

Answer 2

Answer:

208.

Step-by-step explanation:

cost of 15 note book =390.

cost of 1 N.b =390/15

cost of 8 N.B =390/15 ×8

=26 × 8

= 208 Answer