If she wants to put 2 on each invitation, then we multiply the amount of invitations she has by the amount of stickers going on each invitation. 7 times 2 is 14.
She has 10 stickers, and she needs 14 in total, so we subtract 10 from 14 and we get 4.
The negative in front of the second bracket means that it's times by -1 so each of their signs switches: 3m^2+2n-m^2-2n Add like terms 2m^2 the 2n cancels out
