Question

What is the value of x in the equation x – y = 30, when y = 15?

Answer 1

(2/3)(30)=20
30+20=50=(x/5)
(50*5)=x=250 

hope this helps

Answer 2

The value of $x$ in the equation $\frac{x}{5}-\frac{2y}{3}=30$ for $y=15$ is $\fbox{\begin\\\ \math x=200\\\end{minispace}}$.

Further explanation:

The given equation is $\frac{x}{5}-\frac{2y}{3}=30$.

The given equation is a linear equation in two variables.

The general form of linear equation in two variables is $ax+by+c=0$ where $a,b,c\ \text{and}\ c$ are real numbers such that $a\ \text{and}\ b$ are not equal to zero.

The equation is $\frac{x}{5}-\frac{2y}{3}=30$.

Here, the value of $y$ is $15$.

The value of $x$ is calculated by substituting $15$ for $y$ as,

$\dfrac{x}{5}-\dfrac{2\cdot 15}{3}=30$

Now, simplify the above equation as shown below.

$\begin{aligned}\dfrac{x}{5}-\dfrac{2\cdot 15}{3}&=30\\ \dfrac{x}{5}-(2\cdot 5)&=30\\ \dfrac{x}{5}-10&=30\end{aligned}$  

Now, add $10$ on each side of the above equation as,

$\begin{aligned}\dfrac{x}{5}-10+10&=30+10\\ \dfrac{x}{5}&=40\end{aligned}$  

The above expression can be further solved by multiplying $5$ on both side of the equation as,

$\begin{aligned}\left(\dfrac{x}{5}\right)\cdot 5&=40\cdot 5\\x&=40\cdot 5\\x&=200\end{aligned}$  

Therefore, the value of $x$ in the equation $\frac{x}{5}-\frac{2y}{3}=30$ for $y=15$ is $\fbox{\begin\\\ \math x=200\\\end{minispace}}$.

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Answer details

Grade: Middle school

Subject: Mathematics

Chapter: Linear equations in two variables

Keywords: Linear equations in one variable, linear equations in two variables, function, real numbers, solution, solution set, open interval, closed intervals, semi-closed intervals, semi-open interval, values, substitute, multiply, add, subtract, divide.