In a class, the total number of boys and girls is (68). Twice the number of boys plus the number of girls is (112). What is the number of girls?
Answer and explanation
Correct answer: 24
Let the numbers of boys and girls be x and y respectively. Then x+y=68 and 2x+y=112. Subtracting the first equation from the second gives x=44. Therefore, y=68-44=24. Hence, the correct answer is 24. If 26 were chosen, the total would become 70, so it cannot be correct. Exam tip: In such questions, subtracting the equations often eliminates one variable directly.
Frequently asked questions
What is the correct answer to this question?
24
Why is this the correct answer?
Let the numbers of boys and girls be x and y respectively. Then x+y=68 and 2x+y=112. Subtracting the first equation from the second gives x=44. Therefore, y=68-44=24. Hence, the correct answer is 24. If 26 were chosen, the total would become 70, so it cannot be correct. Exam tip: In such questions, subtracting the equations often eliminates one variable directly.
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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