Since the two triangles are similar the ratio will be
56 : x
48 : 6
We can simplify 48 : 6 as 8 : 1 by dividing both 48 and 6 by the factor 6. Then you can compare 8 : 1 and 56 : x. When you do this you'll see that to go from 8 to 56 you have to multiply by 7. So you have to do that for 1 as well. 1 x 7 = 7. Therefore x = 7.
