I dont get this at all plz help fast :0

65 8 7 4 5 6 8 4 3 2 1 9 5 6 4 2 1 6 5 1 5 1 3 2 3 5 multiply the third number in the first row by the seventh number in the third row. add this result to the fifth number in the second row. add to this total ten times the fourth number in the third row. subtract the eighth number in the first row from the result.

Can someone me and do the problem plz so i can understand it more better

X+ y = 5 ; x - y =3 solve using linear combination