24% of 80 is 19.2
120% of 70 is 84
20% of 150 is 30
0.8% of 150 is 1.2
120% of 85 is 102
<span> He could draw a diagram of a rectangle with dimensions x – 1 and x – 6 and then show the area is equivalent to the sum of x2, –x, –6x, and 6.</span>
I'm assuming the given function is f(x) = 15x^2 + 10x.
If so, then,
f(x) = 15x^2 + 10x
f(x) = 15*(x)^2 + 10*(x)
f(-1) = 15*(-1)^2 + 10*(-1) ... note how x is replaced with -1
f(-1) = 15*(1) + 10*(-1)
f(-1) = 15 - 10
f(-1) = 5
Therefore the answer is 5
