our portfolio consists of $75$ shares of CSH and $70$ shares of$$ EJH, which you just bought at $ $21$ and $ $29$ per$$ share, respectively.

a$.$ What fraction of your portfolio is invested in$$ CSH$?$ In$$ EJH?

b$.$ If CSH increases to $ $23$ and EJH decreases to $ $28,$ what is the return on your$$ portfolio?