Respuesta :

Answer:

There are 9 quarters and 3 nickels

Step-by-step explanation:

problems used: 0.5x+0.25y=3.09

x=y+6

so substitute what x is equal to into the problem

0.5(y+6)+0.25y=3.09  <--------- distribute

0.5y+3+0.25y=3.09     <--------- Combine like terms

0.3y+3=3.09 <----------- Subtract 3 on both sided to get y by itself

0.3y=0.9 <------------ Divide by 0.3 on both sides to get what y is equal to

y=3 <-------- now substitute to find what x is equal to

x=3+6

x=9

Answer:

There are 8 nickels and 14 quarters.

Step-by-step explanation:

Let n and q represent the numbers of nickels and quarters present.  

Then q = n + 6 states that there are 6 more quarters than there are nickels.

($0.25)(q) + ($0.05)n = $3.90, in which we substitute n + 6 for q:

($0.25)(n + 6) + ($0.05)n = $3.90

Combining the n terms, we get 0.25n + 0.05n = 3.90 - 0.25*6, or:

                                                           0.30n           = 3.90 - 1.50, or:

             $2.40

n = ----------------------- = 8

               0.30

There are 8 nickels and 14 quarters.

Check:  14 quarters comes to $3.50 and 8 nickels to $0.40, and $3.50 + $0.40 sums up to $3.90.