The value of y varies directly with x. if x = 3, then y = 21. what is the value of x when y = 105?

The value of x when y = 105 is 15 and this can be determined by using the concept of proportionality and the given data.

Given :

The value of y varies directly with x. If x = 3, then y = 21.

The following steps can be used in order to determine the value of x when y = 105:

Step 1 - The concept of proportionality can be used in order to determine the value of x when y = 105.

Step 2 - According to the given data, the value of y varies directly with x. The mathematical expression is given below:

Step 3 - So, the above expression can be written as:

y = kx   --- (1)

where k is the proportionality constant.

Step 4 - Now, substitute the value of (x = 3) and (y = 21) in the above expression.

21 = 3k

k = 7

Step 5 - Now, substitute the value of (y = 105) and (k = 7) in the expression (1).

105 = 7x

x = 15

For more information, refer to the link given below:

link

15

Step-by-step explanation:

varies directly means:

Plug in the given values of x and y to solve for k:  → 7 = k

Next, plug in the k-value of 7 and the given y value of 105 to solve for x:

15 = x

step-by-step explanation:

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value