Question

P = a + b + c. Rewrite this formula having ‘b’ as the subject.
(a). P = a + b + c
(b). a = P + b + c
(c). b = P – a – c
(d). c = a + P + b

Answer 1

- Hint:- Let us first know about the transposition method.
TRANSPOSITION METHOD: When a term moves (transposes) to the other side of the equation, its operation changes to the inverse operation. By doing so, the linear equation stays balanced. This is called the Transposition method and is used to solve linear equations.
The inverse operation of an addition is a subtraction. Multiplication and division are inverse operations.

Complete step-by-step solution -

Let us transpose this equation now: P = a + b + c to get ‘b’ as the subject.
P = a + b + c
We can see that the operation of ‘a’ is ‘+’, i.e. addition. Therefore, when we will transpose ‘a’ to the other side of the equation, the operation of ‘a’ will be ‘-’, i.e. subtraction.
P – a = b + c
Now, we can see that the operation of ‘c’ is ‘+’, i.e. addition. Therefore, when we will transpose ‘c’ to the other side of the equation, the operation of ‘c’ will be ‘-’, i.e. subtraction.
P – a – c = b
Hence, we now have got an equation that has ‘b’ as its subject.
We can also write it as follows: b = P – a – c
Therefore, the correct option for this question is (c) b = P – a – c.

Note:- Let us now know about one more way that is used to solve linear equations using examples.
Example:-
Find the value of ‘x’ in the equation: ‘x – 5 = 2’
This method is called ‘SOLVING LINEAR EQUATION IN ONE SIMPLE STEP’.
So, x – 5 = 2
Adding 5 to both sides of the equation:-
x – 5 + 5 = 2 + 5
x = 7
Hence, the value of ‘x’ is 7.