Write a proportion to find how many points x a student needs to score on a test worth 50 points to get a test score of 78%.?/? =78/?

The answer is:  "39 points" .
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Explanation:
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" x/ 50 = 78/100 " ;   in which "x" equals the number of points needed.

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To solve for "x" ; 
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Look at the denominators:  50 * (what value?) = 100.

→ "100 ÷ 50 = 2" .

→ So;  "50 * 2 = 100" ; 

So, let us look at the numerators:

x * 2 = 78 ; 

↔  2x = 72 ; 

Divide each side of the equation by "2" ; to isolate "x" on one side of the equation ; and to solve for "x" ;
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 →  78 ÷ 2 = 39 ;

The answer is:  "39 points" .
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