Ibarely ask questions but i really need with #3 and a little with 4. on number four i got 1 1/20 which doesn’t seem right. ! due tomorrow!

Let r, g and b represent red, green and blue.

r+g+b = 74

r=g-1

b=r+g

Again, r+g+b = 74.  Let's substitutte r+g for b:  r+g+(r+g) = 74.

Next, let's eliminate r.  Use r=g-1.  Then      g-1  + g + g-1 + g = 74

Combining the g terms,  4g - 2 = 74     => 4g = 76   =>  g = 19

Recall that r=g-1
and 
b=r+g

Find r.  If r=g-1, and g=19, then r = 19-1=18

Find b:  b = r+g = 18+19=37

So there are 37 blue candies, 18 red candies and 19 green candies.

Check:  37+18+19=74 ???  Yes.