Question

3 bags and 4 pens together costs rs 257 whereas 4 bags and 3 pens together costs rs 324 and find the total cost of 1 bag and 10 pens.By substitution method.

Answer 1

Answer:

Rs. 155

Step-by-step explanation:

$Let \ cost \ of \ one \ bag \ is \ Rs \ a\\\\and \ one \ pen \ is \ Rs \ b\\\\Given \ cost \ of \ 3 \ bags \ and \ 4 \ pens \ is \ 257\\\\3a+4b=257 \ ...(i)\\\\Also \ given \ cost \ of \ 4 \ bags \ and \ 3 \ pens \ is \ 324\\\\4a+3b=324 \ ..(ii)\\\\now \ multiply \ by \ 3 \ in \ equation(i) \ by \ 4 \ in \ (ii) \ we \ get\\\\9a+12b=771\\\\12b=771-9a \ ...(iii)\\\\16a+12b=1296\\\\12b=1296-16a\\\\From \ (iii) \ and \ (iv) \ we \ get\\\\761-9a=1296-16a\\\\-9a+16a=1296-771\\\\7a=525\\\\a=75$

$putting \ a=75 \ in (i)\\\\3a+4b=257\\\\4b=257-3\times75\\\\4b=257-225\\\\b=\dfrac{32}{4}\\\\ b=8\\\\we \ get \ cost \ of \ one \ bag \ and \ one \ pen \ is \ 75 \ and \ 8 \ respectively\\\\So \ cost \ of \ 1 \ bag \ and \ 10 \ pens=75+8\times10\\\\cost \ of \ 1 \ bag \ and \ 10 \ pens=75+80=Rs \ 155.\\\\\\Thus, \ get \ we \ our \ answer =Rs \ 155$

Answer 2

Answer:

Step-by-step explanation: