Question

What is the value of x in the equation 3x- 4y =65, when y= 4?

Answer 1

Answer:  The required value of x when y = 4 is 27.

Step-by-step explanation:  We are given to find the value of x in the following equation when y = 4 :

$3x-4y=65~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)$

To find the value of x, first we should write equation (i) as y as the dependent variable.

From equation (i), we have

$3x-4y=65\\\\\Rightarrow 3x=65+4y\\\\\Rightarrow x=\dfrac{65+4y}{3}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(ii)$

Now, substituting y = 4 in equation (ii), we get

$x\\\\\\=\dfrac{65+4y}{3}\\\\\\=\dfrac{65+4\times4}{3}\\\\\\=\dfrac{65+16}{3}\\\\\\=\dfrac{81}{3}\\\\=27.$

Thus, the required value of x when y = 4 is 27.

Answer 2

3x-4y=65

3x=65+4y

x=(65+4y)/3, when y=4

x=(65+4*4)/3

x=(65+16)/3

x=81/3

x=27