Homework Help: Math

Posted by Nicole on Sunday, October 2, 2011 at 12:17am.

Susan has some $2-coins and $5-coins. If there are 18 coins and the total amount of these coins is not less than $75, find the minimum number of $5-coins.

Math - hurrdurrbeedooda, Sunday, October 2, 2011 at 12:54am
Let x = 2$ coins
Let y = 5$ coins

First equation is for the total amount of coins:
x + y = 18

Second Equation is for total amount in dollars in total from the coins:
2x + 5y = $75

Lets isolate for y
x = 18 - y

Sub into second equation
2(18 - y) + 5y = 75
36 - 2y + 5y = 75
3y = 39
y = 13

Therefore, you must have at least 13 $5 coins.

Answer this Question

Related Questions

maths - A bag contained a number of 20cents, 50cents and $1 coins. 1/3 of the ...
math - jeremy has 19 coins of 2 different values. the total value of coins is 1...
Math - Shirley has 18 coins. One sixth of the coins are quarters, one third of ...
math - Sasa had some 20-cent and 50-cent coins. 7/8 of the coins were 20-cent ...
math - lavere has sixty-one coins, all of which are dimes and quaters. if the ...
Math (please help!) - You have 16 coins that are heads up and 18 coins that are ...
grade 9 math!!!!!!!!!! please help - lavre has sixty-one coins, all of whichare ...
MATHS - A PERSON HAS 1&2 RUPEE COINS WITH HIM.TOTAL NUMBER OF COINS WITH HIM...
MATHS - A PERSON HAS 1&2 RUPEE COINS WITH HIM.TOTAL NUMBER OF COINS WITH HIM...
Math - You have 16 coins that are heads up and 18 coins that are tails up. After...

For Further Reading

First Name:
School Subject:
Answer: