The price of one pen is (p) and one notebook is (q). If (3p+2q=185) and (2p+5q=215), what is the value of (q)?
Answer and explanation
Correct answer: ₹25
Using elimination, multiply the first equation by 5 and the second equation by 2: \(15p+10q=925\) and \(4p+10q=430\). Subtracting gives \(11p=495\), so \(p=45\). Substituting in \(3p+2q=185\), we get \(135+2q=185\), hence \(2q=50\) and \(q=25\). Therefore, the correct answer is ₹25. Substituting ₹20 does not satisfy both equations together. Exam tip: in elimination, make the coefficients of one variable equal before subtracting the equations.
Frequently asked questions
What is the correct answer to this question?
₹25
Why is this the correct answer?
Using elimination, multiply the first equation by 5 and the second equation by 2: \(15p+10q=925\) and \(4p+10q=430\). Subtracting gives \(11p=495\), so \(p=45\). Substituting in \(3p+2q=185\), we get \(135+2q=185\), hence \(2q=50\) and \(q=25\). Therefore, the correct answer is ₹25. Substituting ₹20 does not satisfy both equations together. Exam tip: in elimination, make the coefficients of one variable equal before subtracting the equations.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Pair of Linear Equations in Two Variables. Topic: Algebraic methods: Substitution method and Elimination method..
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