If $69-26=66$; $86-34=60$; $35-28=31$, then $77-21=?$

Let's decipher the logic underlying the equations:Consider the numbers as $AB-CD=\text{Result}$.The pattern is: $\text{Result}=(A\times B)+(C\times D)$ Let's test this pattern:$69-26⟹(6\times 9)+(2\times 6)=54+12=66$ (Matches)$86-34⟹(8\times 6)+(3\times 4)=48+12=60$ (Matches)$35-28⟹(3\times 5)+(2\times 8)=15+16=31$ (Matches)Applying the same logic to $77-21$:
$$(7\times 7)+(2\times 1)=49+2=51$$