both of these questions are related, please answer both

5. A unknown solution had a concentration of copper designated at Ccu. A standard solution of copper had a concentration of 61.55ppm. Write an expression for the concentration of copper ([Cu]=) in a solution where 25.00mL of unknown solution was mixed with 3.00mL of copper standard. 6. The solution in question 5 gave an analytical signal of 0.808. The unknown solution alone had an analytical signal of 0.144. What is the concentration of copper in the unknown? (Signal is proportional to concentration; i.e., S=kc )