(-2d^2+s)(5d^2-6s)
= (-2d^2*5d^2 + s*5d^2 -2d^2*-6s + s*-6s
= -10d^4 + 5sd^2 + 12sd^2 - 6s^2
=-10d^2 + 17sd^2 - 6s^2
This is the final result
A = ((B+b)*h)/2
A = ((6+4)*3)/2
A = 15
15 Minutes
You have 8 km in an hour.
Divide all that by two and you'll have 4 km in 30 mins.
Then divide by two again to end up with 2 km in 15 mins.
You could alternatively divide by four from the beginning, but I find this easier.
