A straight line is 180° so....
9x+24 +6x - 24 = 180
15x=180. ( because you have to combine like terms.
X= 12
Well,
we know that we need to accumulate points from x and y to reach 20 points.
since x provide 3 and y provide 4 points, the formula would be :
3x + 4y = 20
or it can be written as :
y = (3x/4)+5
hope this helps
Honestly just use desmos or mathyway
PEMDAS
2(12)x(12)/2
24x12/2
288/2
144