Homework Help: Finding a and b to satisfy somthing, matrices problem!

Hello everyone (TD) hah, our professor has been out of town in CA all week so he hasn't taught us jack and yet we have everything due on monday. So these may be basic problems but i'm still lost. I tried putting them all together in 1 matrix and solving, and i got
1 0 .2
0 1 1
0 0 0
but it was wrong.
Find a and b such that

-5
10 = a
45

1
-1 + b
-3

0
1
6

a = ?
b = ?

Note the above groups of numbers should be in a 3x1 matrix, i just couldn't draw the symbols! and the = a, and + b should be the whole 3x1 matrix = a, and so on. Thanks!