Im trying to learn how to solve myself so please tell me how you found answer

8

Step-by-step explanation:

We can set this up in a ratio. In the picture shown, there is a large triangle and a small triangle inside it.

The ratio for the large triangle would be 21/28.

I got the '21' from '21/28' from doing 15+6.

Now the ratio for the small triangle is 6/x. As x is the unknown value.

To find x, we have to cross multiply and to do that we would do:

21x = 28x6

Simply and you get

21x=168

x=8

Hope this helps! :)

step-by-step :

236 cm 16 time 12 = 192

6 times 7 = 42

192+42