how to solve linear equation in one variable.

Let me help you go through what is all about linear equations and how to solve linear equation in one variable.
what is linear Equation?
A set of linear equations having a regular solution set is called system of coincident linear equations.Find values of three unknowns, given three linear equations in the three unknown variables. Linear equation in three unknowns x, y, z is report of parity of form ax + by + cz + d = 0 where a, b, c, d are real numbers with a ≠ 0, b ≠ 0 and c ≠ 0.
Solving linear equations in one variable
Find the following examples on linear equation in one variable
Examples -
Mr.R is seven times as old as his son. 10 years hence, he will be three times as old as his son. Find their ages.

Solution -
Let the son's age be x years.
Mr.R's age is 7x years.
After 10 years, his son's age will be = (x + 10) years
After 10 years, Mr.R's age will be = (7x + 10) years
By the given condition of the problem
(7x + 10) = 3(x + 10)
7x + 10 = 3x + 30
7x - 3x = 30 - 10
4x = 20 or x = 5
Son's age is 5 years.
Mr.R's age is 7 5 = 35 years
Mr.R's age is 35 years and his son's age is 5 years