Answer:
65%, 2/3, 0.7, 6/8
Step-by-step explanation:
6
Like how

= 36
Square root does the opposite.
Edit: my mistake, it is 6
The variable is b, the coefinet is 1/3
remember
ab-ac=a(b-c)
1/3b-1/3=1/3(b-1)
there, factored
1/3 Probability both are red
red picked first:
6/10
red picked second:
5/9 (9 as first red marble not replaced so 5 red marbles remaining and 4 blue marbles still)
6/10 * 5/10 = 1/3
Hope that helps!!