Answer:
b=-25
Step-by-step explanation:
10= -2/5b
10= -2/5b
------ -------
-2/5 -2/5b
b=-25
Check:
-2/5(-25)=10
10=10
I am assuming this is a triangle.....P = a + b + c
P = 2a - 3 + 2a + 3a + 1....combine like terms
P = 7a - 2 <==
The distance in kilometers in scientific notation 
<h3>Scale factors</h3>
Scale factors are values or constants multiplied with a variable
If Alvin and Simon raced a distance of
kilometers and they need to race 7 times that distance in a kilometer, the distance traveled will be:
- Distance travelled =

- Distance travelled =

Hence the distance in kilometers in scientific notation 
Learn more on distance here: brainly.com/question/23848540