Using substitution:
first you have to express one variable in terms of the other, in this we can express y in terms of x:

Since both expressions are equal to y, you have to equal both expressions like this:

Now you can solve the equation:

Knowing x=10, you can use any of the expressions we found before to find y. In this case I'm going to use y= -x+9 because it's simpler but boy should give you the same result

So, the answer is x=10 and y=-1
He messed up step 2 he added instead of multiplying
To find the area of the triangle you would have to plug in the numbers for this equation: A= Hxb/2
So in your case 14x10/2
140/2= 70 and that would be your answer. Answer:G
Answer:

a=8.182 and b=8
Step-by-step explanation:
Weight of the Empire State Building =
pounds.
Weight of the One World Trade Center building= 88,200,000 pounds.
=
The addition of the two:

Comparing with the form: 
a=8.182 and b=8