Age-related word problems are very common in algebra, particularly in linear equations in one variable for Class 8 mathematics. Let's solve the classic problem: 'Fifteen years from now, Mary's age will be four times her present age. What is Mary's present age?'
This problem tests the ability to convert English statements into algebraic equations.
Always check the answer: If she is 5 now, in 15 years she will be 20. And 20 is exactly four times 5. The answer is verified.
Let Mary's present age be denoted by the variable $x$.
The problem states that after 15 years, her age will be four times her present age. So, we can write the equation as: $x + 15 = 4x$
Therefore, Mary's present age is 5 years.
A linear equation in one variable is an equation that can be written in the form ax + b = 0, where a and b are real numbers and x is a single variable.
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