Answer:
A.
Step-by-step explanation:
you have to find the discriminant
b²-4ac for each equation
if discriminant < 0 no real solutions because will be negative under the squareroot whhan you try to find the roots
if discriminant = 0 there is only one solution
if discriminant > 0 two real solutions
for your given problems
A. discriminant =(-2)²-4*2*15 will be negative
y=100-30x
28 - 7 = -3k
21 = -3k
21/-3 = k
k = -7
x/5 = 3 + 17
x/5 = 20
x = 5*20
x = 100
82 - 12 = 7G/10
70 = 7G/10
70*10 = 7G
700 = 7G
700/7 = G
G = 100
