The Cost for a Guitar Maker to Handcraft X Guitars $C ( x )$

The cost for a guitar maker to handcraft x guitars is given by the function $C ( x )$ . The revenue taken in with the sales of x guitars is given by the function $R ( x )$ . Find the number of guitars that must be sold so that the cost equals the revenue. $C ( x ) = \frac { 1 } { 8 } x ^ { 2 } - x + 30$ $R ( x ) = \frac { 1 } { 4 } x ^ { 2 }$ __________ guitars