37 + 11 = 48 marbles in total.
At our first pull, there is an 11/48 chance that a red will be pulled--the number of red out of the total number.
At the second pull there is a 10/47 chance that the second marble will be red as well--how many red/total are still in there.
From here, we multiply our two fractions together:
11/48 * 10/47
We can do a little bit of simplifying first; 10 and 48 both have a 2 in common:
11/24 * 5/47
Now we multiply our numerators (11 *5) and denominators (24 * 47) and our answer is:
55/1128, or 55:1128
When we divide, we get about 0.04876, which rounds to 4.88%, depending if you want to keep it in fraction, ratio, or percentage form.