60% of 120 is 72. Therefore, Mark has only saved 72 dollars.
We can solve this by setting up a proportion where 864/12 = 504/x. We cross multiply and get 864x = 504 * 12. So 864x = 6048. Divide by 864 on both sides, x = 7.
It would take Charlie 7 hours to drive 504 miles.
Expand it so the expression would equal
5x^2+11x+2=-1
move the negative one over by adding one to both sides
5x^2+11x+3=0
then do the quadratic formula
x=-b+/- (√(b^2-4ac))/2a
where b = 11 a=5 and c=3