The age of john is 9 years.
Algebra is a branch of mathematics that deals with symbols and the arithmetic operations across these symbols. These symbols do not have any fixed values and are called variables. In our real-life problems, we often see certain values that keep on changing. But there is a constant need to represent these changing values. Here in algebra, these values are often represented with symbols such as x, y, z, p, or q, and these symbols are called variables. Further, these symbols are manipulated through various arithmetic operations of addition, subtraction, multiplication, and division, with an objective to find the values.
An algebraic expression in algebra is formed using integer constants, variables, and basic arithmetic operations of addition(+), subtraction(-), multiplication(×), and division(/). An example of an algebraic expression is 5x + 6. Here 5 and 6 are fixed numbers and x is a variable.
Given:
John is 3 years older than Mary.
Five years ago he was four times as old as Mary was then.
let the age of mary be x
John's age= x+ 3
Five years age,
Mary's age= x-5
john's age = x-2
So,
x-2= 4( x-5)
x- 2 = 4x- 20
-3x= -18
x=3
Hence, john's age= 9 years
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