What should come in place of the question mark (?) in the following number series?

Solve 12 / 4 x 3 = ?
Can you please solve 12 / 4 x 3 = ?
The answer is 9. The correct order of operations is to perform the division first (12 / 4 = 3), then multiply by 3 (3 * 3 = ?).

National Mathematics Day 2022: Date, History, Significance, More
National Mathematics Day 2022: Date, History, Significance, More

If a : b = 20:5 then find out the value of (13a-9b): (11a-7b)?
If a : b = 20:5 then find out the value of (13a-9b): (11a-7b)?

A can paint a house in 55 days and B can do it 66 days. Along with C, they did the job in 12 days only. Then, C alone can do the job in how many days?
A can paint a house in 55 days and B can do it 66 days. Along with C, they did the job in 12 days only. Then, C alone can do the job in how many days?