Question

را آزرا What is the value of x in the proportion?

Answer 1

Answer:

Step-by-step explanation:

Cross multiply on both sides

= (x + 1) (21) = 15(x + 3)

= 21x + 21 = 15x + 45

Bringing like terms on one side

21x - 15x = 45 - 21

= 6x = 24

x = 24/6 = 4

Option A is the correct answer

Answer 2

The correct option :

$=\tt (a) \: 4$

Steps to derive correct option :

$= \frac{x + 1}{x + 3} = \frac{15}{21}$

$=( x + 1 )\times 21 = (x + 3 )\times 15$

$= 21x + 21 = 15x + 45$

$= 21x + 21 - 15x = 45$

$= 6x + 21 = 45$

$= 6x = 45 - 21$

$= 6x = 24$

$= x = \frac{24}{6}$

$=\color{plum} \bold{x = 4}$

Let us now place 4 in the place of x and see if the substitution is equivalent to $\frac{15}{21}$ :

$= \frac{4 + 1}{4 + 3} = \frac{15}{21}$

$= \frac{5}{7} = \frac{15}{21}$

$= \frac{5}{7} = \frac{15÷3}{21÷3}$

$= \frac{5}{7} = \frac{5}{7}$

Therefore, the value of x in this proportion = 4