Question

the cost of 18 rulers is ₹ 117. find the cost of a dozen rulers​

Answer 1

$\bold{No.of\:Rulers↑, Cost↑}$

$\bold{No.of\:Rulers ∝Cost}$

$\bold{\dfrac{R_1}{R_2}=\dfrac{C_1}{C_2}}$

$\bold{\dfrac{^{3}\:\cancel{18}}{_{2}\:\cancel{12}}=\dfrac{₹117}{C_2}}$

$\bold{\purple{\:C_2=₹78}}$