Question

Mary multiplied a number by-3.When she added the result to 6,she got 12. What is her number?

Answer 1

Step-by-step explanation

Step 1

set the equation

a) let x represents the number

`number=x`

b) now , translate

`i)Mary\text{ multiplied a number by 3}\Rightarrow x*3=3x`

then

`\begin{gathered} ii)shed\text{ added the result to 6} \\ 3x+6 \end{gathered}`

finally

`\begin{gathered} iii)\text{ she got 12, hence} \\ 3x+6=12 \end{gathered}`

therefore, the equation is

3x+6=12

Step 2

now, solve the equation

`3x+6=12`

The subtraction property of equality states that if the same number is subtracted from both sides of an equation, then the equality still holds, so we can subtract 6 in both sides in order to isolate the term where x is, hence

`\begin{gathered} 3x+6=12 \\ 3x+6-6=12-6 \\ 3x=6 \end{gathered}`

finally, apply the division property of equality and divide both sides by 3

`\begin{gathered} 3x=6 \\ (3x)/(3)=(6)/(3) \\ x=2 \end{gathered}`

so, the number is 2

I hope this helps you