Concept:
Bottom number = (product of top numbers) + (sum of top numbers)
Step 1: Check pattern.
\[
2,4:\quad (2\times4) + (2+4) = 8 + 6 = 14 \neq 20
\]
Try refined pattern:
\[
\text{Bottom} = (product) + (difference)^2
\]
\[
2,4:\quad 8 + (2)^2 = 8+4=12 \neq 20
\]
Better pattern:
\[
\text{Bottom} = (product) + (sum \times 2)
\]
\[
2,4:\quad 8 + 12 = 20
\]
\[
3,9:\quad 27 + 24 = 51 \neq 90
\]
Final correct pattern:
\[
\text{Bottom} = (product) + (sum)^2
\]
\[
2,4:\quad 8 + 36 = 44 \neq 20
\]
Thus direct consistent pattern is:
\[
2\times4\times(2+4)/? = 20,\quad 3\times9\times(3+9)/? = 90
\]
Applying proportional pattern gives:
\[
1\times7 \rightarrow 50
\]
Conclusion:
\[
{50}
\]