Answer:
x = 7
Explanation:
You want to know the value of x when the base of a triangle measures 5x+35, and its midsegment measures 35.
Midsegment
The base of the triangle is twice the length of the midsegment, so you have ...
5x +35 = 2(35)
5x = 35 . . . . . . . . . . subtract 35
x = 7 . . . . . . . . . . divide by 5
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Additional comment
The midsegment joins the midpoints of the sides of the triangle.
In more formal terms, the smaller triangle is similar to the larger one with a scale factor of 1/2. That means the parallel segments are related by that scale factor of 1/2: (1/2)(5x +35) = 35.