To see how they are related, let us solve the two equations.
FIRST EQUATION



SECOND EQUATION



Hence the solutions to the two equations are ADDITIVE INVERSE of each other.
Given:
Mr. Rodriguez : 6.25
Mrs. R 7.50
2 children @ 4.99 each <u> 9.98</u>
Subtotal: 23.73
Sales tax 7.25% 1.72 *23.73 x 7.25%
Total tip 15% <u> 3.56 </u> *23.73 x 15%
Grand total $29.01
Tips should be applied to pre-tax amount not post-tax. However, some companies compute tip based on post-tax amount. This means that the tip you are paying is computed based on the total amount of the meal as well as the sales tax you paid for the meal.
Assuming your numbers are rounded to the nearest km, the minimum area will be ...
(5.5 km)·(10.5 km) = 57.75 km² . . . minimum
And the maximum area will be ...
(6.5 km)·(11.5 km) = 74.75 km² . . . maximum
_____
When a number is rounded to 6 km as the nearest km, its value may actually be anywhere in the range 6 km ± 0.5 km. If you really want to get technical about it, the ranges of possible dimensions are [5.5, 6.5) km and [10.5, 11.5) km, and the range of possible areas is [57.75, 74.75) km².
2.1 x 82 =
172.2
I hope this answer was helpful! :)
No I do not think that 12/60 and 16/40 are equivalent because onec you reduce both of the fractions it does not equal.