Four times the sum of a number and 15 is at least 120. let x represent the number. find all possible values for x.

Four times the sum of a number and 15 is at least 120
Let ‘x’ represent the number.
 "The sum of a number and 15"
This can be written mathematically as x + 15
 Given that 4 times this sum is at least 120,
This means that 4 times the sum is greater than or equal to 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 answer should be c.