Which system of linear equations can be solved using equation [x y] = [ 1/4 3/4 1 2][28 -12]?

This is about circle theorems. someone asap : (

Y=21.95x+10 y=22.45x solve by substitution

Julia bought 7 hats a week later half of all her hats were destroyed in a fire. there are now only 12 hats left with how many did she start