Question

What is the value of x? ​

Answer 1

Answer:

x = 7

Step-by-step explanation:

Similar

The two triangles

1) the one making up the peak of the large triangle

2)the large triangle  

are similar. That is because the 2 bases are parallel and corresponding angles are equal. The third angle at the peak is common. So by AAA they are similar.

Proportion

Therefore the sides are in proportion.

5/40 = 3/(2x + 10)

Solution

Cross multiply

5*(2x + 10) = 40*3

Remove the brackets on the left. Combine the right.

10x + 50 = 120          

Subtract 50 from both sides

10x + 50 - 50 = 120 - 50

10x = 70

Divide by 10

10x/10 = 70/10

x = 7