Plug the points that are given in.
We need a third equation to solve. We are given the vertex; so the symmetrical line of this parabola is x=3. Reflect the other given point, (2,0), over this line to get your third point (4,0).
0=16a+4b+c. 3rd equation minus second equation is 12a+2b=0, second equation minus the first is -5a-b=2. -10a-2b=4. 2a=4, a=2, b=-12, c=16. (2,-12,16)
Let Jim's salary be J.
Jim spends 3/5 of his salary on transport. J-3/5J=2/5J is left.
1/8 of his remaining salary is (1/8)*(2/5J)=2/40J=1/20J, which is how much he spends on food.
He gives 1/10J to his mother.
So J-3/5J-1/20J-1/10J=5/20J=1/4J left, and this amount is equal to $1325.
(a) Jim spends 1/20 of his salary on food ($265)
(b) Jim's salary is 4*1325=$5300.