pleasee help mee ;w;

Answer:
Step-by-step explanation:
It is assumed PQS and RQS are similar triangles.
The ratio of corresponding sides is equal:
Substitute side lengths and solve for x:
The ratio of sides remains same
[tex]\\ \sf\longmapsto \dfrac{PQ}{QS}=\dfrac{RQ}{RS}[/tex]
[tex]\\ \sf\longmapsto \dfrac{21}{15}=\dfrac{5x-16}{3x-4}[/tex]
[tex]\\ \sf\longmapsto \dfrac{7}{5}=\dfrac{5x-16}{3x-4}[/tex]
[tex]\\ \sf\longmapsto 7(3x-4)=5(5x-16)[/tex]
[tex]\\ \sf\longmapsto 21x-28=25x-80[/tex]
[tex]\\ \sf\longmapsto 80-28=25x-21x[/tex]
[tex]\\ \sf\longmapsto 4x=52[/tex]
[tex]\\ \sf\longmapsto x=13[/tex]