Me with this word problem and fill in blanks

This is pretty much the same as the last one I did. I'll go slow.

We have two numbers we're looking for, so we give them letters. Let's call them a for arbequina and g for green; they're the respective amounts in pounds.

In these problems we're give a total for a+g and then another total, which is going to be something times a plus something times g.  Here we have

a + g = 8

That says the two kinds of olives together weight 8 pounds.

9 a + 25 g = 8(15) = 120

This second equation says if we sell the arbequina for $9 a pound and the green for $25 a pound we'll get $120, which is $15 a pound times eight pounds.

Once the equations are set up we solve by eliminating one of the variables.

g = 8 - a

9 a + 25 (8 - a) = 120

9 a  + 200 - 25 a = 120

-16 a = - 80

a = 5

g = 8 - a = 3

Check:

9 (5) + 25 (3) = 45 + 75 = 120        good