Which expression is equivalent to 15x + 21y? a: 3(5x + 7y) b: xy(15 + 21) c: 3xy(5 + 7) d: 5( 3x + 4y) pls tell me the correct answer to this and how its correct (step by step pls because i really dont get it)

The answer is A: 3(5x + 7y)

This is because, if you look at 15x + 21y, the greatest common factor would be 3, as there is no x in 21y and no y in 15x. This means that 3 would need to be outside of the bracket, and A is the only option with just 3.

Also, you know that A is correct because 3 × 5x = 15x, and 3 × 7y = 21y.

I hope this helps!

Maybe fx = lxl because of the way the x is positioned is that what he