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

.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 Link

calculista calculista · Answer 2 · 2018-12-29T00:02:06+01:00

Answer:

the number of nickels is [tex]5[/tex]

Step-by-step explanation:

Let

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

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

we know that

[tex]1\ nickel=\$0.05[/tex]

[tex]1\ dime=\$0.10[/tex]

so

[tex]0.05x+0.10y=3.75[/tex] -------> multiply by [tex]100[/tex] both sides

[tex]5x+10y=375[/tex] -------> equation A

[tex]y=7x[/tex] -------> equation B

Substitute equation B in equation A and solve for x

[tex]5x+10[7x]=375[/tex]

[tex]5x+70x=375[/tex]

[tex]x=375/75[/tex]

[tex]x=5[/tex]

Find the value of y

[tex]y=7(5)=35[/tex]