Answer: 
Step-by-step explanation:
The pool of rats from which the researcher is drawing participants is composed of the following:
23 male albino rats
21 male spotted rats
35 female albino rats
11 female spotted rats
Total rats = 23+21+35+11 =90
After drawing first rat , total rats remained = 89

The probability of choosing a male albino rat and then either a female albino rat or a male spotted rat = 
We can express Benjamin's age with x, we can express Luca's age as y.
x-6=2y
So, if x=12
2y=6
y=3
Therfore, Lucas is 3 years old
12 and 20 are both divisible by 4
12 ÷ 4 = 3
20 ÷ 4 = 5
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The simplest ratio would be 3:5