standard_description: Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
problem_activity: Problem 1
The perimeter of a rectangle is 54 cm. If the length is 2 cm more than a number and the width is 5 cm less than twice the same number, what are the dimensions of the rectangle?
Problem 2
A plot of land for sale has a width of
$$x$$
feet and a length that is 8 feet less than its width. A farmer will only purchase the land if it measures 240 square feet. What value for
$$x$$
will cause the farmer to purchase the land?


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