Answer:

Step-by-step explanation:
Hello, please consider the following.
We have two equations:
(1) -2x - 4y = 20
(2) -3x + 5y = -25
5*(1)+4*(2) gives
-10x - 20y -12x + 20y = 100 - 100 = 0
-22x = 0
x = 0
I replace in (1)
-4y = 20
y = -20/4 = -5
There is one solution x = 0, y = -5
Hope this helps.
Do not hesitate if you need further explanation.
Thank you
Answer:
10
Step-by-step explanation:

1-2 = -1
If that's what u mean
ANSWER: 8/21
Step:
1. Find the GCF (Greatest Common Factor)
The two denominator which is the bottom number have to be the same ALWAYS when adding and subtracting the fraction. So to find the GCF, you keep multiplying until you see the same number, only use the bottom number to find the GCF
7: 7, 14, 21, 28
3: 3, 6, 9, 12, 15, 18, 21, 24, 27
GCF= 21
2. 5/7 -1/3
Multiple both to get 21
5/7 x 3/3 = 15/21
1/3 x 7/7 = 7/21
3. Sove
15/21 - 7/21
= 8/21