We will have the following:
*First: We write the expressions described in the problem:
[tex]A=3B[/tex][tex]A+B=140[/tex]*Second: We replace the first expression in the second and solve for B:
[tex](3B)+B=140\Rightarrow4B=140[/tex][tex]\Rightarrow B=35[/tex]So, the fastest speed for bird B is 35 mph.
Now, using this information we determine the speed of bird A:
[tex]A=3(35)\Rightarrow A=105[/tex]So, the fastest speed for bird A is 105 mph.