A bank contains 30 coins, consisting of nickels, dimes, and quarters. There are twice as many nickels as quarters and the remaining coins are dimes. If the total value of the coins is 3.35. What is the number of each type of coin in the bank?

Quarters: 7

Dimes: 9

Nickels: 14

Step-by-step explanation:

Bank --> 30 coins

Base Equations:

N+D+Q=30

5N+10D+25Q=335

Equation 1: 2Q=N

Equation 2: D=30-(N+Q)

                   Substitute Equation1 :  D=30-(2Q+Q)

                   D=30-3Q

0.05(2Q)+0.10(30-3Q)+0.25Q=3.35

0.10Q+3-0.3Q+0.25Q=3.35

0.5Q+3=3.35

0.5Q=0.35

Q=7

if Q=7, N= 2*Q

N=14

D=9

Check Step:

7*25=175

14*5=70

9*10=90

175+70+90=335

Correct

a: 1/6, j: 1/4

step-by-step explanation: you are welcome

a is the right answer