Answer triangle RST is congruent to the triangle LMK
If you move the triangle vertically you can find the congruency of two sides and one angle
Use Heron's Formula:
s means semi-perimeter = (50 + 31 + 18) / 2 = 99 / 2 =
49.5
area = sq root [(s * (s-a) * (s-b) * (s-c)]
area = sq root [(49.5 * (s-a) * (s-b) * (s-c)]
This will NOT form a triangle. The longest side (50) is greater than the sum of the other 2 sides.
Source:
http://www.1728.org/trianinq.htm
8=2x2x2
2^3 as required base 2

Actually Welcome to the concept of calculations of bills.
The bill calculation goes as equation,
y = $250 + n*($10)
here, n = number of lines,
1.) For n = 2 , Y = cost = 250 + 20 = $270
2.) for n = 4 , Y = $290
3.) for n = 6 , Y = $310
4.) for n = x, Y = $250 + x*($10)
for lastly 12 members we get as,
Y = 250 + (12)*(10) = 250+120 = $370