An isosceles triangle is a type of triangle where 2 sides are equal.
Picture out 2 triangles with the same base length. 
On the first triangle, its legs are twice the length of the legs of the second triangle.
To put it into variables, let:
     B = the same base length of the two triangles
     A = the length of one leg the smaller triangle
    2A = the length of one leg of the bigger triangle
Given:    Perimeter of smaller triangle = 23cm
              Perimeter of bigger triangle = 43cm
Recall the formula for solving the perimeter of a triangle:
      Perimeter = A + B + C
   
where, A, B, and C are the legs of the triangle
Since the triangle involved is an isosceles triangle, therefore, we can say that
        Perimeter = 2A + B     ,   2 legs are equal ( A=C )
Substituting the given perimeter value to the formula. 
    
23cm = 2A + B                    ⇒   equation 1  (smaller triangle)
43cm = 2(2A) + B                ⇒   equation 2  (bigger triangle)
Simplifying equation 2.
                                    43cm = 4A + B
  (rearranging)             B = 43cm - 4A        ⇒ equation 3
Substituting equation 3 to equation 1:
   (equation 1)              23cm = 2A + B
                                    23cm = 2A + (43cm - 4A)
                                    23cm = -2A + 43cm
                                    2A = 43cm - 23cm
                                    2A = 20cm  ⇒   length of the leg of the bigger triangle
                                     A = 10cm   ⇒   length of the leg of the smaller triangle
To solve for the base length, just substitute the value of A to equation 3
     (equation 3)       B = 43cm - 4A
                               B = 43cm - 4(10cm)
                               B = 3 cm
Final Answer:
• For the smaller triangle, the length of the sides are 10cm, 10cm, and 3cm
• For the bigger triangle, the length of the sides are 20cm, 20cm, and 3cm
        
             
        
        
        
Your answer would be on eof the three
15/8
1.875
1 7/8
Hope this helps...
        
                    
             
        
        
        
Are those all your options? the answer would be 3x+10= 28 but you dont have it as a multiple choice.
        
             
        
        
        
<h3>
Answer:  x = 16</h3>
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Explanation:
On that diagram, the unmarked angle above the (6x-8) is equal to (5x+12). This is because the unmarked angle and the angle marked with (5x+12) are corresponding angles. Corresponding angles must be congruent if you want line m to be parallel to line n.
From here we add up (5x+12) and (6x-8) and set that sum equal to 180. Solve for x
We get the following:
(5x+12)+(6x-8) = 180
5x+12+6x-8 = 180
(5x+6x)+(12-8) = 180
11x+4 = 180
11x = 180-4
11x = 176
x = 176/11
x = 16