His work should have looked like this.
2x + y = 5
x − 2y = 10
y = 5 − 2x
x − 2(5 − 2x) = 10
x − 10 + 4x = 10
5x − 10 = 10 When he added in both sides, he subtracted 10 from 10,
5x = 20 instead of adding 10 from 10 to make 20.
x = 4
2(4) + y = 5
8 + y = 5
y = -3
Answer:
Step-by-step explanation:
f(3) = 8^3 + 7 = 512 + 7 = 519
Answer:
74.72
Step-by-step explanation:
Given
mean
Standard deviation 
For Top 25%

and Z value for 75 % is 0.6744
Thus score which separates the Top 25% of students is


The answer is B, the green is f(x)=x^2 and the red one is g(x)=f(2x).