Question

Jimmy has seven times as many dimes as nickels. Their value is $3.75. How many nickels does he have?

Answer 1

.05n + .10d = 3.75
d = 7n

now we sub
.05n + .10(7n) = 3.75
.05n + .70n = 3.75
.75n = 3.75
n= 3.75/0.75
n = 5

d = 7n
d = 7(5)
d = 35

so he has 5 nickels and 35 dimes

Answer 2

the number of nickels is
`5`

Explanation:

Let

x------> the number of nickels

y------> the number of dimes

we know that

`1\ nickel=\$0.05`

`1\ dime=\$0.10`

so

`0.05x+0.10y=3.75` -------> multiply by
`100` both sides

`5x+10y=375` -------> equation A

`y=7x` -------> equation B

Substitute equation B in equation A and solve for x

`5x+10[7x]=375`

`5x+70x=375`

`x=375/75`

`x=5`

Find the value of y

`y=7(5)=35`