Question 895770
the pool
20*15=300 
4 foot wide sidewalk
(20+4)*(15+4)-300=
24*19-300=
456-300=156 sq ft 
156*25=$3900

4 foot wide sidewalk
(20+5)*(15+5)-300=
25*20-300
500-300=200 sq ft
200*25=$5000


6 foot wide sidewalk
(20+6)*(15+6)-300=
26*21-300
546-300=246 sq ft
246*25=$6150

BTW You can't buy sq ft of concrete. Concrete is a solid which is sold in cubic yards.

I recommend the 6 ft wide sidewalk so there is plenty of room. 
Who cares about the price! Safety first!