Simplify the following expression:
25x+20x+16x·5x-4x
=25x·5x+25x·-4x+20x·5x+20x·-4x+16x·5x+16x·-4x
=125x-100x+100x-80x+80x-64x
=125x-64x
Properties of Exponents:
am·an=am+n
aman=am-n
amn=am·n
ab-n=ban
a0=1
125x-64x