In Unknown Change problems, the middle number is the unknown number.
Example 1 - Unknown Change (minus)
162 apples were in an apple tree. A gust of wind blew the tree, and some apples fell to the ground. 124 apples remained. How many apples fell from the tree?
(Answer = 38)
Example 2 - Unknown Change (plus)
Rochester, NY received 1 foot of snow in 24 hours. Over the next few days, it continued snowing. When the skies finally cleared, there was a total accumulation of 5 feet, 6 inches of snow. How much snow fell after the first day?
(Answer = 4 feet, 6 inches)
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Because its cut
it is unknown becasue of the change of pennys evry year
True.
Usually in algebra the term "unknown" is used for a variable ( commonly designated as x ) you are trying to solve for. For instance the mathematical expression 2 + x = 5 may be presented to the student as a problem. The answer is to solve for the unknown or x. The solution would be x = 3
It usually involves some kind of dividing. Take a basic problem like n x 5 = 45, where n is the unknown factor. Divide both sides of the equation by 5 so that n stands alone. 45 divided by 5 is 9, so n = 9