Question

Lindsay is 555 years younger than Mark. Seven years ago, the sum of their ages was 313131.

Let l be Lindsay's age and let mmm be Mark's age.
Which system of equations represents this situation?
Choose 1 answer:

Answer 1

L=M-5

(L-7)+(M-7)=31

Step-by-step explanation:

Khan Academy says it's right

Answer 2

System:

• Equation 1: L = M - 5
• Equation 2: L + M = 45

Step-by-step explanation:

Rewrite the question to delete the typos:

• Lindsay is 5 years younger than Mark. Seven years ago, the sum of their ages was 31. Let l be Lindsay's age and let mmm be Mark's age.Which system of equations represents this situation?

1. Name your variables:

• Lindsay's age: L

• Mark's age: M

2. Translate each verbal statement into an algebraic expression:

a) Lindsay is 5 years younger than Mark

• L = M - 5 ← first equation

b) Seven years ago, the sum of their ages was 31

• L - 7 + M - 7 = 31

• Simplify:

L + M - 14 = 31

L + M = 31 + 14

L + M = 45 ← second equation

3. Write the two equations:

System:

• Equation 1: L = M - 5
• Equation 2: L + M = 45