SOLUTION: A math quiz is worth 100 points.There are 13 problems on the quiz.Some of the problems are worth 5 points, and the rest are worth 12 points.How many of each kind of problem are on

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Question 492945: A math quiz is worth 100 points.There are 13 problems on the quiz.Some of the problems are worth 5 points, and the rest are worth 12 points.How many of each kind of problem are on the quiz?
Answer by nerdybill(7384) About Me  (Show Source):
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A math quiz is worth 100 points.There are 13 problems on the quiz.Some of the problems are worth 5 points, and the rest are worth 12 points.How many of each kind of problem are on the quiz?
.
Let x = number of problems worth 12 points
then
13-x = number of problems worth 5 points
.
12x + 5(13-x) = 100
12x + 65-5x = 100
7x + 65 = 100
7x = 35
x = 5 (number of problems worth 12 points)
.
number of problems worth 5 points:
13-x = 13-5 = 8