Greater Than/Less Than Multiple Numbers

Happy New Year,
I need a formula that would do the following.
The value in A1 is equal to 15 from, greater than 15 from, or less than 15 from the values in B1:D1. If it's at least 15 away from all three it's TRUE, if not FALSE.
Example:
A1: 135
B1: 150
C1: 120
D1: 100

Thank you for any and all help.