color(red)((-20x - 12)(-19x - 15))
doing this is like doing 2(x + 4)
you times the number outside the brackets, color(blue)(2), with everything inside the brackets, color(blue)((x + 4))
2 xx x = color(blue)(2x
2 xx 4 = color(blue)8
color(blue)(2x + 8)
2(x + 4) becomes 2x + 8
So, with color(red)((-20x - 12)(-19x - 15))
You times these together first...
(color(red)(-20x) - 12)(color(red)(-19x - 15))
like...
-20x xx -19x = color(blue)(380x^2
-20x xx -15 = color(blue)(300x
then you do the same with...
(-20x color(red)(-12))(color(red)(-19x - 15))
like...
-12 xx -19x = color(blue)(228x
-12 xx -15 = color(blue)(180)
When you put everything together, you get something like this
color(blue)(380x^2 + 300x + 228x + 180
And when you solve that...
380x^2 color(blue)(+ 300x + 228x) + 180
380x^2 color(blue)(+ 528x) + 180
