Gladys S. answered 07/19/20
ASVAB, Algebra, Geometry, and PreCalculus Tutor
"When Mark counted the money he collected from his paper route he had $9.75 all in quarters and dimes. The ratio of dimes to quarters was 7 : 5. How many coins of each type were there?"
We can make an equation from this information.
The ratio of dimes to quarters was 7 : 5 tells us that dimes and quarter are related in the proportion
7X: 5X.
We will use 7X for the number of dimes and 5X for the number of quarter in the solution of the problem.
The value of each dime is 5 cents. The value of each quarter is 25 cents. The value of their sum ( in cents) is 975.
So the equation becomes:
( number of dimes).10 + (number of quarters).25 = 975
or
(7X). 10 + (5X).25 = 975
70X + 125X = 975
195X = 975
X = 5 ( divide both sides by 195)
recall that we are looking for the number of dimes, and that is equal to 7X
so number of dimes = 7X = 35
also, number of quarters is 5X = 25.