The value of y varies directly with x. If x = 15, then y = 12. What is the value of y, when x = 21?

y = 16.8

Step-by-step explanation:

Given that y varies directly with x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition x = 15 when y = 12, that is

12 = 15k ( divide both sides by 15 )

= k, so

k = 0.8 y = 0.8x ← equation of variation

When x = 21, then

y = 0.8 × 21 = 16.8

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question: use the following table of a school bus during morning pickups to calculate its average speed between 2.8 km and 4.2 km

answer: 42 km/h

explanation: 1.4/0.033 42.42424 = 42 km/h

question answered by

(jacemorris04)