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:
Speed of sound is 340 meter per second.
Step-by-step explanation:
Let the speed of sound = x meter per second.
It is given that,
The new mode of travel has the speed 170 meter per second, which is 50% less than the speed of sound.
So, we get,
x - 50%x = 170
i.e. x - 0.5x = 170
i.e. 0.5x = 170
i.e. x = 340 meter per second
Hence, the speed of sound is 340 meter per second.
Answer:
Beef Sirloin is the least expensive meat per pound