Question

Can someone help me please?

Answer 1

Remark
What you can do is solve this system of equations
Let the 2 point questions = x
Let the -1 point questions = y
Let the 0 point questions = n

2x - y = 24
x + y + n = 20  So start by letting x = 14 (just a random number) Solve the first equation.

2x - y = 24
2*14 - y = 24
28 - y = 24  Subtract 28 from both sides.
- y = 24 - 28
- y = - 4
y = 4

Now use the second equation to solve for n
14 + 4 + n = 20
18 + n = 20
n = 20 - 18
n = 2

Answer 1
x = 14
y =  4 
n = 2   Total 20.

This time lets try x = 15 and solve for y
2*15 - y = 24
30 - y = 24
- y = - 6
y = 6 

15 + 6 + n = 20 This obviously will not work. 15 right is too many to be this circumstance. n would have to be -1 and that isn't possible.

Try x = 13
2x - y = 24
2*13 - y = 24
26 - y = 24
-y = 24 - 26
-y = -2
y = 2

Now use the second equation.
x + y + n = 20
13 + 2 + n = 20
15 +n = 20
n= 5

So Answer 2 is
x = 13
y = 2
n = 5