Question

The age of Sachin before Y years was X years, then his age after 4 years will be _______ years.
A. $X + Y + 4$
B. $X - Y - 4$
C. $Y - X + 4$
D. $X - Y + 4$

Answer 1

Hint: Start by taking the person’s present age equal to a variable and then set the other equations on the basis of that. Get at least 2 equations for 2 variables and solve those 2 equations to get the value of the first variable, then put the value of the first variable to any of the equations and obtain the value of the second variable.
Let, the present age of Sachin be $a$ years.
Therefore, before years, the age of Sachin would have been $\left( {a - Y} \right)$ years which is given to be equal to $X$ years.
Therefore, on equating, we get,
\[\left( {a - Y} \right) = X\]
\[a = X + Y\]
Therefore, his present age is \[\left( {X + Y} \right)\] years.
His age after \[4\] years will be present age plus $4$, which is \[\left( {a + 4} \right)\] years,
Age= \[\left( {X + Y + 4} \right)\]
Therefore, Option A is the correct answer
Note: In this type of questions students get confused as X and Y are already given. Here X and Y are constants so assume different variables and solve pairs of linear equations.