Respuesta :
Answer:
Dimes: 11 , Nickels: 7
Step-by-step explanation:
Let's say the number of dimes ⇒ x and the number of nickels ⇒ y:
We know the total number of coins, 18 , such that we can format one equation to be:
x + y = 18
We also know the total cost of dimes and nickels, 1.45 dollars. Here we (in general) know that the cost of a dime is 0.1 dollars and the cost of a nickel is 0.05 dollars so that 0.1x represents the total cost of dimes if x represents any number, and 0.05y represents the total cost of nickels if y represents any number. Knowing this, let us format another equation to be:
0.1x + 0.05y = 1.45
So, we now have two equations:
x + y = 18, and
0.1x + 0.05y = 1.45
Let's alter the first equation as such, so that x is isolated:
x + y = 18
x = 18 - y
Now let's substitute the this value of x in the second equation and solve for y:
0.1x + 0.05y = 1.45
0.1(18 - y) + 0.05y = 1.45
1.8 - 0.1y + 0.05y = 1.45
1.8 - 0.05y = 1.45
-0.05y = -0.35
y = 7 nickels
Knowing the number of nickels, substitute the value of y into the first equation:
x + y = 18
x + (7) = 18
x = 11 dimes
