Answer:
Step-by-step explanation:
Just translate the words to numbers. Twice the number of dimes is 2d . Five less means subtract 5 from that. thats the nunber of nickels: n
So your first equation is n = 2d- 5
you know that the value of a nickel is 5 and the value of a dime is 10 and the total value is 115. (skip the decimals for now!) It's all cents. (that should make sense!)
The second equation is 5n + 10d = 115
Substitute the value of n (2d-5) from the first equation into the place of n in the second equation.
5(2d -5) + 10d = 115 now Distribute
10d -25 + 10d =115 and solve for d (add 25 to both sides abd combine d's)
10d + 10d = 115 + 25
20d = 140 divide both sides by 20
d = 7 Put that value in place of d in the first equation and solve for n
n= 2(7) -5 That's 14-5 so n=9
Check values in either equation: 5n + 10d= 115
5(9) + 10(7) = 115
45 + 70 = 115 TRUE! so Jon has 9 nickels and 10 dimes.
