Question

If twelve less than 3 times a number is 27, then the number is ____?
A) 29
B) 39
C) 65
D) 13

Answer 1

Hint:
first of all, we’ll assume the required number as x then we’ll find 3 times of this number. After this, we’ll subtract 12 from that number. this will give us a linear equation in one variable and we’ll solve that for known x.

Complete step by step solution:
At first, Let the number be x.
Now according to the question, multiplying the number by 3 and then subtracting 12 from it is will get 27.
So, the equation will be
 $3x-12=27$
Solving
 $\Rightarrow 3x-12=27$
 $\Rightarrow 3x=27+12$
 $\Rightarrow 3x=39$
 $\Rightarrow x={\displaystyle \frac{39}{3}}$

So, x = 13
Therefore, the required number is 13.

Note:
The basic rule of algebra regarding the linear equations is, we need to get as many equations as many knowns we have. Given problem was univariate. which mean of a single variable. we also have a double variable or even triple variate linear equation in mathematics. They have their own methods to solve.