The answer is: 15 .
__________________________ _____
{Note: If this is a physics problem ; and the formula: "F = m*a" is for:
"Force = mass * acceleration" ; be sure that the correct units are used!}.
_______________________________________________________
Step-by-step explanation:
_______________________________
F = m * a ;
Given m = 5 ;
a = 3 ;
___________________
F = 5 * 3 = 15 .
_____________________