Question

A person has 20 coins, all nickels and dimes, worth one dollar and 40 cents. How many nickels are there?

If n = number of nickels and d = number of dimes, which system of equations represents the problem?

n + d = 20 and n + d = 1.40
n + d = 20 and 5n + 10d = 1.40
n + d = 20 and 5n + 10d = 140

Answer 1

Answer:The correct answer to this question would be:

n+d=20 and 5n+10d=140

Explanation:

Answer 2

A.)n + d = 20 and n + d = 1.40 That's wrong because if n + d = 20, it can't equal 1.40 too!

B.)n + d = 20 and 5n + 10d = 1.40 That's wrong because the left side of 5n + 10d = 1.40 is in cents but the right side is in dollars.

C.)n + d = 20 and 5n + 10d = 140 That's right, for the left side of 5n + 10d = 140 is in cents and the right side is also in cents, because $1.40 equals 140 cents.