Check the picture below, based that the directrix is a horizontal line, and the vertex is below it, we know is a vertical parabola, and is opening downwards.
notice the distance "p" from the vertex to the directrix, is just 1/2
Melinda is saving at the rate of 60/5 = $12 per week
Marcus is saving $14 per week
Difference is $2
Melinda is savinf $2 less than marcus each week
The answer is a 3% jewnsnsnddksk
Answers: a = 49
b = 10
c = 105