4^2 + b^2 = 12^2
16 + b^2 = 144
B^2 = 144-16
B^2 = 128
B= 11.3
28 miles per hour is your answer 154 divided by 5.5, simple math hon :) good luck.
I am unsure about the very last problem but I can help with the first two
1) (y+1)+4
If we combine the numbers 1 and 4, we get +5 and can isolate the numbers from the variable.
This would give us

2) (6*r)*7
remember that we do not have to explicitly state 6*r
Instead, we can write it as 6r
this helps us get rid of the parentheses
now we can write it as

I hope this helps!:)
Answer:
The correct option is C
Step-by-step explanation:
if f(x)= x3 + x2 - 20x
Replace f(x) by y
y = x3 + x2 - 20x
0 =x3 + x2 - 20x
x3 + x2 - 20x = 0
Take out x as a common:
x(x2+x-20)=0
Find factors of x2+x+20.
x(x^2+4x-5x-20) = 0
x{x(x+4)-5(x+4)}=0
x(x+4)(x-5)=0
Set x= 0
x=0 , x+4=0 , x-5 =0
x=0, x=0-4 , x=0+5
x=0, x= -4, x=5
x=(0,5,-4)
The correct option is C....