What you need to do is add the two equations and combine like terms to get h(x). Refer to the photo for a better explanation.
y = x^2 + 2x...eqn 1
y = 3x + 20...eqn 2
subst for y in eqn 1...
=> x^2 +2x = 3x +20
=> x^2 - x - 20 =0
=> (x-5) (x+4) =0
=> x = 5 or -4
for x =5, y = 35 (sub for x in eqn 1 or 2)
for x = -4, y = 8 (sub for x in eqn 1 or 2)
The fourth one should be the correct answer
Given parameters:
Percentage gain = 300%
Selling cost last year = $2420
Unknown:
Selling cost this year = ?
Solution:
To solve this problem;
Profit percent = 
300 = 
3 = 
S- 2420 = 7260
S = $9680
To make a 300% gain, Jefferson Middle school needs a $9680 from fundraiser sales this year.