Find the value of y for a given value of x, if y varies directly with x.

Question

If y=−252 when x = 84, what is y when x = 74?
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Answer 1

To find the value of y when x = 74, we first need to determine the constant of variation, also known as the constant of proportionality.

Since y varies directly with x, we can write the equation:

y = kx

Where k is the constant of proportionality.

To find the value of k, we can use the given information that y = -252 when x = 84. Substituting these values into the equation, we get:

-252 = k(84)

Now we can solve for k by dividing both sides of the equation by 84:

k = -252/84
k = -3

Now that we have the value of k, we can use it to find y when x = 74:

y = kx
y = -3(74)
y = -222