Answer :
At first you may get confused but look at those numbers carefully :)
as you see first result is divisible buy one of the product (second product in all cases is unknown)
so let's check where it will lead us :)
[tex]6/2=3[/tex]
[tex]12/3=4[/tex]
[tex]20/4=5[/tex]
[tex]30/5=6[/tex]
[tex]42/6=7[/tex]
Now you can clearly see that every number was multiplied by number 1 higher than itself.
[tex]2*(2+1)=6[/tex]
[tex]3*(3+1)=12[/tex]
[tex]4*(4+1)=20[/tex]
etc...
it means that after equation sign there should be [tex]90[/tex] because
[tex]9*(9+1)=90[/tex] :)
as you see first result is divisible buy one of the product (second product in all cases is unknown)
so let's check where it will lead us :)
[tex]6/2=3[/tex]
[tex]12/3=4[/tex]
[tex]20/4=5[/tex]
[tex]30/5=6[/tex]
[tex]42/6=7[/tex]
Now you can clearly see that every number was multiplied by number 1 higher than itself.
[tex]2*(2+1)=6[/tex]
[tex]3*(3+1)=12[/tex]
[tex]4*(4+1)=20[/tex]
etc...
it means that after equation sign there should be [tex]90[/tex] because
[tex]9*(9+1)=90[/tex] :)