-- Each nickel is worth $0.05, so if there are 'N' nickels, their value is 0.05N .
-- Each dime is worth 0.10, so if there are 'D' dimes, their value is 0.10D .
-- We know that (N + D) = (number of nickels + number of dimes) = 141
You later edited your question, and said the total value in the pig
is actually $10.85, so ...
-- We also know that (0.05N + 0.10D) =
(value of the nickels+value of the dimes) = 10.85
Now we have two equations ... exactly what we need when there are
two unknown quantities to be found.
N + D = 141
0.05N + 0.10D = 10.85
Multiply each side of the
second equation by 10 : 0.5N + D = 108.5
Now your two equations
look like this: N + D = 141
0.5N + D = 108.5
Subtract the second one
from the first one: 0.5N + 0 = 32.5
Multiply this one by 2 : N = 65 There are 65 nickels in the pig.
How about the dimes ? That's easy now. You know there are
141 coins in there all together, so the number of dimes is just
(141 - 65) = 76 dimes.
====================================
Check:
Total value = 0.05N + 0.10D
What's the total value if N=65 and D = 76 ?
0.05(65) + 0.10(76) = 3.25 + 7.60 = 10.85 It checks. yay !
