To solve for \( b \) using the given values \( n = 56 \) and \( a = 70 \), we need additional context or a mathematical relationship involving these variables. Since that context is not provided, I can't determine the value of \( b \).
If there's a specific formula or equation you have in mind that relates \( n \), \( a \), and \( b \), please provide it, and I would be happy to help solve for \( b \).