To find the missing term, we need to identify the pattern in the given grid of numbers. Let's examine the first two columns, which are complete.

In the first column, the numbers are 6, 8, 3, and 51. Let's try to find a relationship between the top three numbers (6, 8, and 3) and the bottom number (51). One possible pattern is to multiply the first two numbers and add the third number: 6 * 8 + 3 = 48 + 3 = 51. This matches the bottom number of the first column.

Let's test this pattern on the second column. The numbers are 15, 4, 5, and 65. Applying the same rule: 15 * 4 + 5 = 60 + 5 = 65. This also matches the bottom number of the second column.

Since the pattern (First number * Second number) + Third number = Bottom number holds for the first two columns, we apply the same rule to the third column to find the missing term.

In the third column, the numbers are 20, 5, 20, and ?. The first number is 20, the second number is 5, and the third number is 20.
Missing term = (First number * Second number) + Third number
Missing term = (20 * 5) + 20
Missing term = 100 + 20
Missing term = 120.

The missing term is 120.