The answer is 200. you would multiply 1000 by 80% giving you 800. 800 people didnt know the name so that leave 200 people did.
2a + 3b = 6 --> Equation 1
5a + 2b = 4 --> Equation 2
Equation 1 * 5 --> 10a + 15b = 30
Equation 2 * 2 --> 10a + 4b = 8
Equation 1 - Equation 2 --> 11b = 22 --> b = 2
Sub b=2 in Equation 1 (or 2, either works):
2a + 3b = 6
2a + 3(2) = 6
2a + 6 = 6
2a = 0
a = 0
b = 2, a = 0
It is not possible to draw here. I am attaching the diagram along with the answer. I hope the diagram will be clear for you to understand. I also hope that this is the answer that has actually come to your desired help. You can draw it with pencil, if you want to make it perfect.
267.3
1 2 3 4 STAYS THE SAME
5 6 7 8 9 ROUNDS UP