Answer:
[(1.9+2.4)x5.7/2]-[(2.4x5.7)/2]
Step-by-step explanation:
You take the area of the large triangle (which has a base of (1.9+2.4) and height of 5.7) and subtract the area of the small right triangle (whose base is 2.4 and height is 5.7)
Alternatively, you could use Heron's formula, but I doubt that's what they're looking for.
18/1. Just divide both sides of your fraction by 3
in 1980 it was about 20%
in 1990 it was about 30%
about a 10% increase
in 2000 it was just under 40% so almost a 10% increase
so for estimating you can say it is increasing by about 10% every 10 years
so in 2010 you can estimate about 50% are unmarried
Since 16 and 25 are perfect squares you can factor the first part.
4^2-5^2(b+3)^2
=(4-5(b+3))(4+5(b+3))
=(4-5b-15)(4+5b+15)
=(-11-5b)(19+5b)
Which can be expanded if necessary,
= -209+150b-25b^2