Answer: .75g + 4 = 7 [remove spaces where necessary]
Step-by-step explanation: $4 is the flat rate for a helmet, so we add that into the equation. Since "g" represents one group of pitches and it costs 75¢, we add it into the equation as .75g. On the other side of the equal sign we put the amount of money spent, in this case 7 - to find out how many groups of pitches he bought we just solve the equation. In this case g = 4.