There are 130 pennies in the jar
Step-by-step explanation:
We have a jar of coins
We need to find the number of pennies in the jar
Assume that there are p pennies and d dimes in the jar
∵ There are p pennies and d dimes in the jar
∵ There are 309 coins in the jar
∵ All the coins in the jar are pennies and dimes
∴ p + d = 309 ⇒ (1)
∵ The total value of all coins in the jar is $ 19.2
∵ $1 = 100 cents
∴ $19.2 = 19.2 × 100 = 1920 cents
∵ 1 penny = 1 cent
∵ 1 dime = 10 cents
∴ p + 10 d = 1920 ⇒ (2)
Now we have system of equations, we can solve them to find p
∵ p + d = 309 ⇒ (1)
∵ p + 10 d = 1920 ⇒ (2)
- Multiply equation (1) by -10 to eliminate d
∵ (-10)(p) + (-10)(d) = (-10)(309)
∴ -10 p - 10 d = -3090 ⇒ (3)
Add equations (2) , (3)
∴ -9 p = -1170
- Divide both sides by -9
∴ p = 130
There are 130 pennies in the jar
Learn more:
You can learn more about the system of equations in brainly.com/question/3739260
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