<u>To find the constant of proportionality:</u>
⇒ must define constant of proportionality
⇒ <em>Constant of Proportionality: ratio of two proportional values at a </em>
constant value
⇒ (in this case) two proportional values are x and y
<u>The ratio between x and y is equal to</u>

<u>Answer:</u> <u>55</u> or <u>Choice 1</u>
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Hope that helps!
0.5x + 78.2 = 287
-78.2 -78.2
subtract 78.2 on both sides you will then get 0.5x = 208.8 you will then divide by 0.5 and the answer is x = 417.6