Question

How do you write an equation representing thirteen less than a number x is three?

Answer 1

Hint: Here, we need to write a first-degree equation, because according to the question we need to find the equation in terms of ‘x’ with power=1. Make sure to look for words which mention inequality in sentence, they are a major help in forming equations. For example- “more than” implies addition and “less than” implies subtracting a smaller number from the bigger number.

Complete step by step answer:
In the question, we need to focus on the part “…thirteen less than number x is three? “ to get our equation.
Whenever we need to change a sentence into an equation, we need to see whether any inequality is mentioned there or not. In this case, the question says that thirteen is less than a number which is named ‘x’, so mathematically it means that
$\Rightarrow 13 < x....(i)$.
This implies that only thirteen can be subtracted from a number ‘x’ to get a desired outcome, since ‘x’ is the bigger value in this case.
Now, we will subtract thirteen from ‘x’, because according to the sentence given in the question, we need to remove thirteen from ‘x’ to get a constant value 3.
So, our L.H.S. will look like $x-13$.
Since, subtracting 13 from an unknown number gives us the value three, it implies that the L.H.S.=R.H.S.=3.
Therefore, our equation will be
$\Rightarrow x-13=3$ .

Note:
Here, we cannot write $13-x=3$ will be the equation for the given sentence in question, because it would contradict the inequality that we derived in (i). This is one of the most common mistakes that students can make, so beware of it.