U just need to add all the numbers together
City hall to post office = 6 1/2 miles = represented by f
city hall to library site = 1 1/4 miles = represented by d
library site to post office = unknown. = represented by e
City hall to library site PLUS library site to post office IS EQUAL to city hall to post office
d + e = f
1 1/4 + e = 6 1/2
find e.
e = 6 1/2 - 1 1/4
e = 13/2 - 5/4
e = (13*2)/(2*2) - 5/4
e= 26/4 - 5/4
e = (26-5)/4
e = 21/4
e = 5 1/4 distance from library site to post office.
To check:
d + e = f
1 1/4 + e = 6 1/2
1 1/4 + 5 1/4 = 6 1/2
6 2/4 = 6 1/2
6 1/2 = 6 1/2
53+53+53+53+53+53=318
if you add 53 six times you get 318
She need 3 bags since the area of the triangle is base x height /2
Area 20*6=120
120/2=60
60/20= 3 since each bag covers 20m^2