Please help multiply this is with square roots. Thanks!

(2√5 - 6√2)(4√5 + 12√2)
please help multiply, I am lost !! thanks!

I'm gonna break it all down. Square roots are rounded to nearest thousandth

(2√5 - 6√2)
2√5=4.472
6√2=8.481
4.472 - 8.485= -4.013

(4√5 + 12√2)
4√5=8.944
12√2=16.970
8.944 + 16.970=25.914

-4.013 * 25.914=-104

(2√5 - 6√2)(4√5 + 12√2)
= 40 - 24 sqrt 10 + 24 sqrt 10 - 144
= -104