If we say there are 100 cars in a lot (It's an arbitrary number. You can use any number you want), Matthew can wash 100 cars in 14 hours or 7.14 cars an hour. Arianna can wash 100 cars in 11 hours or 9.09 cars an hour. Together, in an hour they can wash 7.14 + 9.09 or 16.23 cars. So to wash 100 cars it would take them 100/16.23 = 6.16 or about 6 hours.
You can do this with variables as well.
Matthew has a rate of x/14 while Arianna has a rate of x/11. Together their rate is x/14 + x/11= x/y
Divide both sides by x, you would get 1/14 + 1/11 = 1/y
Solve for y which would be around 6 hours.
The greatest number of plants he can have in a row is 27 and 2 rows of 27. 27 carrot seeds and 27 onion bulbs. Since he uses 27 of each he is left with 0 onion bulbs and 27 carrot seeds.
The triangle inequality requires that the sum of the shorter sides, a, b of a triangle be greater than the third side c.
This means that
a+b > c
If the third side is the longest, then a=6, b=9, and c<15
That makes 15 an impossible side.
If the third side x is less than 9, then
6+x<9, that makes
x<9-6=3.
That makes 2 an impossible side.
So the possible sides are 4,7,10,12,
First, find the actual difference / spread between the buy and sell rates:
$0.7714 - $0.7621 = $0.0093.
To find the percentage, we need to divide either given amount ($0.7621 or $0.7714) and to multiply the result by 100%:
($0.0093 / $0.7714) * 100% = 1.21%