Step-by-step explanation: multiply both sides by 9m-7 then bring down your 10
that's about all I can remember so your on your own from that point it's been a while since I've did this sorry mate
So for this, I will be using the substitution method. Firstly, subtract both sides in the second equation by 2x: 
Next, substitute y in the first equation with 7-2x, then solve for x from there:

Now that we got x, substitute it into either equation to solve for y:

In short, x = 1/2 and y = 6.
Answer:
8.9 cm
Step-by-step explanation:
We have

Answer:
20. 300π m³
21. 457 1/3 π cm³
Step-by-step explanation:
20. r = 10 ÷ 2 = 5
V = 5² × 12 × π = 25 × 12π=300π m³
21. r = 14 ÷ 2 = 7

V = 457 1/3 π cm³
Answer:
-1
Step-by-step explanation:

Hope this helps!