If
and
, then you can replace
in either equation with the equivalent expression given by the other equation. In this case, you have

and you can solve for
.

Then
.
For the second system, you can write


Then substitute this into the second equation and you get


so that

Answer:
He needs 16 ounces of raisins and 8 ounces of nuts
Step-by-step explanation:
Let
x -----> the number of ounces of raisins
y -----> the number of ounces of nuts
we know that
x+y=24 -----> equation A
x=2y -----> equation B
Solve the system by substitution
Substitute equation B in equation A and solve for y
(2y)+y=24
3y=24
y=8 ounces of nuts
Find the value of x
x=2(8)=16 ounces of raisins
therefore
He needs 16 ounces of raisins and 8 ounces of nuts