Answer :
Assuming you made an error typing the question out, and the formula should say 30g, as it's $30 a round:
[tex]30g + 75 = 375[/tex]
[tex]30g =375-75 \\30g = 300 \\g=300/30 \\g=10[/tex]
[tex]30g + 75 = 375[/tex]
[tex]30g =375-75 \\30g = 300 \\g=300/30 \\g=10[/tex]