X∈ab or x∈ac,
So x∈a and x∈b, or x∈a and x∈c,
So x∈a and x∈b+c,
or vice versa, Dallas to the auditorium That is ab+ac=a(b+c).
Similarly (a+c)(a+b)=a+bc.
So ab+ac=a(b+c)≤a≤a+bc=(a+c)(a+b).
Is it okay?