Cogito
Algebra 1 · Chapter 5 · Lesson 3
Systems in Context
Two unknowns, two conditions.
11 problems · about 23 minutes · A-CED.A.3
Figure — use these to answer the problems
Warm Up
Straightforward practice. Get the method working first.
4 problemsx + y = 12 and x − y = 2. What is x?
Answerx + y = 10 and x − y = 4. What is x?
AnswerSame system. What is y?
AnswerHow many equations are needed for two unknowns?
Answer
Build It Up
The same ideas with more to keep track of.
3 problems2x + y = 12 and y = 4. What is x?
Answer20 coins are 5p and 10p, worth 150p. If there are 10 tens, how many fives?
AnswerOrder the steps for a system word problem.
Write 1 to 4 in the boxes to put these in order.
- Name both unknowns
- Write one equation per condition
- Solve the system
- Answer in the words of the problem
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
4 problemsx + y = 9 and x = 2y. What is y?
AnswerSame system. What is x?
AnswerThe Count
a + c = 15 and a = 7. What is c?
AnswerThe Money
7 adults at £8 each. How much, in pounds?
Answer