Answer:
10 days: ofc there is an easier way to do this but i did my own way down below :)
Explanation:
in 1 day
cowboys: 300+25 is 325
saints: 700-15=685
in 2 days:
cowboys: 325+25 is 350
saints: 685-15 is 670
in 3 days:
cowboys: 350+25 is 375
saints: 670-15 is 655
in 4 days:
cowboys: 375+25 is 400
saints: 655-15 is 640
in 5 days:
cowboys: 400+25 is 425
saints: 640-15 is 625
in 6 days:
cowboys: 425+25 is 450
saints: 625-15 is 610
in 7 days:
cowboys: 450+25=475
saints: 610-15 is 595
in 8 days:
cowboys: 475+25 is 500
saints: 595-15 is 580
in 9 days:
cowboys: 500+25 is 525
saints: 580-15 is 565
in 10 days:
cowboys: 525+25 is 550
saints: 565-15 is 550
in 10 days, they will have the same number of followers