Let's represent the price of the horse with the variable 'h' and the price of the saddle with the variable 's':
h + s = 5000
h = 4s
Because we can substract s from both sides on the first equation:
h = -s + 5000
Because h = 4s and -s + 5000, we know that:
4s = -s + 5000
5s = 5000
s = 1000
Because we know that the saddle costs 1000, 5000 - 1000 = 4000, so:
The horse costs $4000, and the saddle costs $1000