Our values are,
[tex]d=7.7m[/tex]
[tex]d= \downarrow[/tex]
A) As the symbol not change both have the same direction, so
Magnitud is,
[tex]c= 7.7*7.2 = 55.44m[/tex]
b) As the symbol change the direction of vector '6.1' is [tex]\uparrow[/tex]
The magnitud will be [tex]= 6.1*7.7 = 46.97m[/tex]