The price of 10 chairs is equal to that of 4 tables. The price of 15 chairs and 2 tables together is Rs. 4000. The total price of 12 chairs and 3 tables is:

1Rs. 3500
2Rs. 3750
3Rs. 3840
4Rs. 3900

Answer:- 1

Explanation:-

Solution:

\begin{aligned} Let the cost of a chair and that of table \\ be R s . x and R s . y respectively . \\ Then, 10 x = 4 y o r y = \frac{5}{2} x \\ ∴ 15 x + 2 y = 4000 \\ \Rightarrow 15 x + 2 \times \frac{5}{2} x = 4000 \\ \Rightarrow 20 x = 4000 \\ ∴ x = 200 \\ So, y = (\frac{5}{2} \times 200) = 500 \\ Hence, the cost of 12 chairs and 3 tables \\ = 12 x + 3 y \\ = R s . (2400 + 1500) \\ = R s . 3900 \end{aligned}

$\eqalign{ & {\text{Let}}\,{\text{the}}\,{\text{cost}}\,{\text{of}}\,{\text{a}}\,{\text{chair}}\,{\text{and}}\,{\text{that}}\,{\text{of}}\,\,{\text{table}} \cr & \,{\text{be}}\,Rs.\,x\,{\text{and}}\,Rs.\,y\,{\text{respectively}}. \cr & {\text{Then}},\,10x = 4y\,\,\,or\,\,\,y = \frac{5}{2}x \cr & \therefore 15x + 2y = 4000 \cr & \Rightarrow 15x + 2 \times \frac{5}{2}x = 4000 \cr & \Rightarrow 20x = 4000 \cr & \therefore x = 200 \cr & {\text{So}},\,y = \left( {\frac{5}{2} \times 200} \right) = 500 \cr & {\text{Hence,}}\,{\text{the}}\,{\text{cost}}\,{\text{of}}\,{\text{12}}\,{\text{chairs}}\,{\text{and}}\,{\text{3}}\,{\text{tables}} \cr & = 12x + 3y \cr & = Rs.\,\left( {2400 + 1500} \right) \cr & = Rs.\,3900 \cr}$