Question 640575
Let b = # of blue caps sold and g = # of gold caps sold


If b blue caps are sold at $6 a piece, then he gets 6b dollars just from the blue caps sold.


Likewise, if g gold caps are sold at $7 each, then he gets 7g dollars from just the gold caps.


So in total, he gets <font color="red">6b+7g</font> dollars


If y is the total amount of money from selling all the caps, then <font color="red">y=6b+7g</font> is the earnings equation.