Sarah and Rachel each have apps on their phones.
The number of apps on Sarah’s phone can be represented by x.
• The number of apps on Rachel’s phone is 4 times the number of apps on Sarah’s phone.
• The total number of apps on both girls’ phones is 115.
What is x, the number of apps on Sarah’s phone?
Let x be the number of apps on Sarah's phone.
The number of apps on Rachel's phone is 4*x.
The total number of apps is x + 4*x = 5*x.
To find x, we need to solve the equation 5*x = 115.
Dividing both sides of the equation by 5, we get x = 115/5 = 23.
Therefore, the number of apps on Sarah's phone is 23. Answer: \boxed{23}.