I need help with this algebra problem ?please!!!!?

1)
8x^2 - 20x + 10x - 25
= 8x^2 + 10x - 20x - 25
= (8x^2 + 10x) - (20x + 25)
= 2x(4x + 5) - 5(4x + 5)
= (4x + 5)(2x - 5)

2)
15x^2 + 16 + 4
= 15x^2 + 20
= 5(3x^2 + 4)

3)
8x^2 - 10xt - 3t^2
= 8x^2 + 2xt - 12xt - 3t^2
= (8x^2 + 2xt) - (12xt + 3t^2)
= 2x(4x + t) - 3t(4x + t)
= (4x + t)(2x - 3t)

See what "intellec" made of 16+4(!)

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1)(4x(2x-5))+5(2x-5)
=(4x+5)(2x-5)