Question

solve for x? (attached figure)

Answer 1

(30+x)/30 = 35/20

20(30+x)=35*30
600+20x=1050
20x=450
x=22.5

Answer 2

Good answerfrom watchmatch but alternatively see the problem as a ratio issue.
The dividing line is parallel to the top line as the angles are equal as stated.
Therefore...
20:30 = 35: 30 + x
Multiply first ratio by a factor 7 and the second by a factor 4...
140:210 = 140: 4(30 + x) = 140: 120 + 4x
Therefore equating RHSs
210 = 120 + 4x
Subtract 120 from both sides
90 = 4x
divide boith sides by 4
22.5 = x

...just a thought to consider.