Question

9 1 point Jonah has 20 nickels and dimes. In total, he has $1.75. Use question 7 to find out how many dimes Jo Type your answer... Previous

Answer 1

Jonah has 15 dimes.

Step by step explanation:

Since question 7, tells us that we have to use the following equations to solve the system:

Let x be the nickels

Let y be the dimes

`\begin{gathered} x+y=20\text{ (1)} \\ .05x+.10y=1.75\text{ (2)} \end{gathered}`

We can use the substitution method to solve the system, isolate y in equation (1), and then plug it into equation (2)

`y=20-x\text{ (1)}`
`\begin{gathered} .05x+.10(20-x)=1.75 \\ \end{gathered}`

Now, solve for x.

`\begin{gathered} .05x+2-.10x=1.75. \\ -.05x=1.75-2 \\ -.05x=-0.25 \\ x=(-0.25)/(-0.05) \\ x=5 \end{gathered}`

That means Jonah has 5 Nickels. Now to solve for y(dimes), substitute x=5 into equation (1)

`\begin{gathered} y=20-x \\ y=20-5 \\ y=15 \end{gathered}`

Jonah has 15 dimes.