and 15 is at least 120. Let x represent the number. Find all possible values for x.

the complete question is
Four times the sum of a number and 15 is at least 120. Let x represent the number. Find all possible values for x.

let
x---------> represent the number

we know that
Four times the sum of a number and 15 is at least 120
This can be written mathematically as
 4(x + 15) >= 120
Solving for x 
 4(x + 15) >= 120 
4x + 60 >= 120 
4x >= 120 – 60 
4x >= 60 
x >= 60/4 
x >= 15 

x is greater than or equal to 15 
the solution is the interval [15,∞)