Four years ago,the sum of the ages of a mother and her two daughters was $x$ years. What will be the sum of their ages after two years?

Draw the graphs of the pair of linear equations $x+y=10$ and $x-y=4$. Determine the coordinates of the vertices of the triangle formed by these linear equations and the $X$-axis.

While arranging the students of standard $X$ in rows,if two rows are reduced,then one more student has to be arranged in each of the remaining rows. If three more rows are formed,then one student has to be taken off from each of the previously arranged rows. Find the total number of students in the class.

Solve the pair of linear equations $2x + y = 40$ and $x + y = 30$. If the solution satisfies the equation $y = mx + 6$,find the value of $m$.

The ratio of the present ages of Rajan and Jay is $3:2$. After five years,the ratio of their ages will be $4:3$. Find the present ages of both.

Solve the following pair of linear equations by the method of substitution: $x + y = 7$ and $5x + 12y = 7$.