Answer:
t = d/S
Step-by-step explanation:
S = d/t
Cross multiply
S x t = d
Divide both sides by S
S/S x t = d/S
t = d/S
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: -2x + 3/2
Step-by-step explanation:
Simplify the expression.
1 mg = 0.001 grams. therefore 2000 mg = 2 grams