Let's denote the quantities of each type of cookie sold by:
• A = # of chocolate chip cookies,
,
• B = # of sugar cookies,
,
• C = # of peanut butter cookies.
From the statement, we know that:
• Bod sold five times as many chocolate chips as peanut butter: A = 5C,
,
• Bod sold seven fewer sugar than chocolate chip: B = A - 7,
,
• Bod sold 9 peanut butter cookies: C = 9,
Replacing the value C = 9 in the equation of A we find that: A = 5 * 9 = 45.
Replacing the value A = 45 in the equation of B we find that: B = 45 - 7 = 38.
Answer
• Bod sold A = 45 butter cookies,
,
• Bod sold B = 38 sugar cookies,
,
• Bod sold C = 9 peanut butter cookies.