there are 6 numbers on each cube:
1) The probability of rolling a 4 on the red number cube is 1/6
2) The probability of rolling a number less than 3 on the blue number cube is 2/6 (Since you can roll 1 or 2 which are both less than 3)
Since you have an AND between two probabilities you must multiply them together:
Answer: (1/6)*(2/6) = 2/36 or 1/18
Hope this helps !