Question

a collection of 30 coins worth $5.50 consist of nickels, dimes and quarters, rhere are twice as many dimes as nickels ,how many quarters are there

Answer 1

n + d + q = 30

get all the values in terms of one variable; the variable they give you is "n".

n = n
d = 2n
q = 30-n-2n = 30-3n

remember these relationships; they come in handy at the end.

We know this:

n(.05) + 2n(.10) + (30-3n)(.25) = 5.50 ; solve for "n".

Answer 2

.05n +.20n -.75n + 7.50 = 5.50 combine like terms.

-.50n = -2.00 ; multiply each side by (-1)

.50n = 2.00 ; divide each side by (.50)

n = 2/.5 = 20/5 = 4

n=4

d=2(4) = 8

q=30 - 4 - 8 = 30-12 = 18