Solve the equation for E. What is a pitchers ERA if he allows 5 earned runs in 18 innings pitched

Question

To find a baseball pitchers earned run avg.  (ERA), you can use the formula Ei = 9r, where E represents ERA, i represents number of innings pitched, and r  represents number of earned runs allowed. Solve the equation for E.  What is a pitchers ERA if he allows 5 earned runs in 18 innings pitched?

Answer 1

This is phrased more complicatedly than it needs to be, and if you're not a baseball person it's not fair!

 

They want to know how many earned runs the pitcher gives up in  9 innings, based on how many he gives up in 18...