Answer:
x=10
Step-by-step explanation:
The two triangles are similar since each triangle is the same shape of right triangle but different sizes. To find x, write a proportion between two equal ratios of side lengths.

Solve by cross multiplying.
28(3x) = 20(4x+2)
84x = 80x + 40
4x = 40
x=10
a+b+c=9 and a2+b2+c2=35 then by using identity
(a+b+c)2=a2+b2+c2+2ab+2bc+2ca,we get the answer 9x9=35+2(ab+bc+ca)
2(ab+bc+ca)=9x9-35
2(ab+bc+ca) =81-35then we get ab+bc+ca=46/2 so ab+bc+ca=23