PLEASE CAN ANYONE TELL ME HOW TO CALCULATE THE SIZE OF THE FORCE OF FRICTION???? AN EQUATION OR IF YOU LOVE Science CAN YOU CALCULATE IT

A BOY WITH A MASS OF 70KG SITTING ON A SKATEBOARD (5 KG) IS PUSHED DOWN A CORIDOOR (2 M) . IT TAKE HIM 3.1 SECONDS TO REACH THE END. CALCULATE THE SIZE OF THE FORCE OF FRICTION?????
PLEASE HELP IM DESPERATE IL DO ANYTHING

Ah, I remember my first sugar frosted captain crunch.

There is always further reading about Niche Blueprint 2 here.