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!:)
you can use 3 quarters and 2 pennies
Answer: 11/12
Step-by-step explanation:
7/12 and 1/3 don’t have the same denominator, so you can’t just add them right away. You have to give them the same bottom number. 1/3 = 4/12, so you can do it like this:
7/12 + 4/12 = 11/12
11/12 is in simplest form, so that should be correct! Hope this helps! :)
About 400 marbles. You simply set up a proportion and solve it as I did in the photo attached.