Forming & Solving Equations Quiz

1. A number $n$ has 5 added to it, then the result is doubled to give 30. Which equation represents this?

• A. $2n+5=30$
• B. $2(n+5)=30$
• C. $n+5=2(30)$
• D. $5(n+2)=30$

2. A rectangle has length $(x+2)$ cm and width $x$ cm with perimeter 24 cm. Find $x$.

• A. $x=4$
• B. $x=5$
• C. $x=6$
• D. $x=10$

3. A rectangle has area $x(x+3)=40$. Solving gives $x=5$ or $x=-8$. Which value is correct for the width, and why?

• A. $x=-8$, because it satisfies the equation
• B. $x=5$, because a length cannot be negative
• C. Both are correct
• D. Neither is correct

4. Two numbers have a sum of 15 and a difference of 3. What are the numbers?

• A. 9 and 6
• B. 10 and 5
• C. 8 and 7
• D. 12 and 3

5. Three interior angles of a triangle are $x$, $x+10$ and $2x$. Form and solve an equation for $x$.

• A. $4x+10=180$, $x=42.5$
• B. $x+10+2x=180$, giving three separate equations
• C. $x + (x+10) + 2x = 180$, so $x=42.5$
• D. $4x = 180$, so $x=45$