Question

помогите сделать дз

Answer 1

a) y-5x-y/7xy= -5x/7xy= -5/7y
b) (a²+81b²-18ab)(1/a-9b)= (a-9b)²• 1/a-9b= a-9b

a)2,5:25=0,1
b) 0,144-17,6= -17,456