Respuesta :

AB = midsegment

ON = 2 × AB

5x + 7 = 2 × 3x 

5x + 7 = 6x

x = 7 

But the midsegment = 3x

Midsegment = 3 × 7

Midsegment = 21
ON = 2AB

2·3X = 5X+7

6X-5X=7

X=7

AB = 3X = 21 units