Solving by Elimination
r + s = -6
r - s = -10
x = 4y
2x + 3y = 22
8a + 5b = 9
2a - 5b = -4
y = x - 2
3x - y = 16
A piggy bank contains 15 coins consisting of quarters and nickels. The total value of the coins is $2.55. Which system of equations can be used to determine the number of quarters, q, and the number of nickels, n, in the piggy bank?
What is 9 quarters and 6 nickels?
2x + 3y = 6
3x + 5y = 15
y = 3x - 1
7x + 2y = 37
A new spiral notebook contains 20 fewer sheets than a new composition book. The total number of sheets of paper in 3 new spiral notebooks and 2 new composition books is 440. Which system of equations can be used to find s, the number of sheets of paper in one new spiral, and c, the number of sheets in one new composition book?
What is 80 pages per spiral notebook and 100 pages per composition book?
2a - 4b = 12
-8a + 16b = -48
3s - 2t = 4
t = 2s - 1
Mrs. Bird teaches 5 math classes per day and Mr. Smith teaches 7 math classes period day. Mrs. Bird's total students are 41 less that Mr. Smith's total students. The number of students in one of Mr. Smith's classes is 3 less than the number of students in one of Mrs. Bird's classes. What is the number of students in each teacher's class?
What is 31 students in Mrs. Bird's class and 28 students in Mr. Smith's class?
(1/3)x + (1/4)y = 10
(1/3)x - (1/2)y = 4
t + u = 12
t = (1/3)u
Emily and Sydney searched their house for dimes and nickels. They found a total of 40 coins. When they counted the money there was $3.10. How many dimes and nickels did Emily and Sydney find?
What is 22 dimes and 18 nickels?