Question

Write a real world problem that can be modeled by the equation 1.25x=0.75x+50

Answer 1

This is not really an equation that can be used to model anything as there is only one variable. see this.
1.25x-0.75x = 50
0.5x = 50
x=100
It can be solved and therefore does not have an input and an output required to model anything