Answer:
x = 10
Step-by-step explanation:
If the triangles are similar, then the corresponding sides are in proportion:
[tex]\dfrac{20}{20+8}=\dfrac{3x}{4x+2}[/tex]
[tex]\dfrac{20}{28}=\dfrac{3x}{4x+2}[/tex]
[tex]\dfrac{20:4}{28:4}=\dfrac{3x}{4x+2}[/tex]
[tex]\dfrac{5}{7}=\dfrac{3x}{4x+2}[/tex] cross multiply
[tex]5(4x+2)=(7)(3x)[/tex] use distributive property a(b + c) = ab + ac
[tex](5)(4x)+(5)(2)=21x[/tex]
[tex]20x+10=21x[/tex] subtract 20x from both sides
[tex]10=1x\to x=10[/tex]
