$$10u + 50u = 600$$  Thus, $$1u = 10$$, in total we have $$2u=20$$ 
Su Li has the same number of ten-cent and fifty-cent coins. The total value is ＄$$6$$. How many coins does she have in all? 

  * $$10$$ 
  * $$20$$ 
  * $$36$$ 
  * $$60$$ 
  * None of the above 