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:
90
Step-by-step explanation:
4/15 which is our fraction distance/time
our other fraction is 24/x (x is our variable to find our time)
Now we are doing the buultterfly method
set it up
now multiply 4*x= 4x
15*24=360
now divide 4x ÷ 4 to get our variable alone
do the same to the other side
4 ÷ 360= 90
so x= 90 which is our missing number
To start off, you can divide the right side of the equation by x to get rid of most of the x's so you get the polynomial x^4 - 10x^2 + 9. This means that f(x) = x^4 - 10x^2 + 9x. By factoring the right side of the equation, you get f(x) = (x^2 - 1)(x^2 - 9). I think the minimum value is 1 and the maximum value is 3.
Multiply the second equation by -2. This will cancel out the y