Solving Two-Step Equations
Lesson 5
Write an equation for each statement and solve to determine the unknown number.
1. The sum of a number and twenty is eighty-seven.
2. The quotient of a number and four is negative six.
3. A number decreased by three tenths is one and two tenths.
Target: Solve two-step equations.
Solve the equation for x. Check the solution.
8x – 3 = 85 + 3 + 3 8x = 88 8 8 x = 11
8(11) – 3 = 88 – 3 = 85
Solve the equation for x. Check the solution.
59
2 x
55
9)7(x
9 9
x 63
25759
63
Use an equation mat to illustrate and solve the equation 2x – 4 = 6.
Set up the mat.
Add four positive chips.
Divide into equal groups.
Solution: x = 5
Eight more than 3 times a number is 29. Write and solve an equation to find the value of the number.
3x + 8 = 29 – 8 – 8 3x = 21 3 3 x = 7
3(7) + 8 = 21 + 8 = 29
Solve each equation for x.
1. 4x + 5 = 49
2.
3. 5 – 2x = 25
83
20 x
Why is it important to show your work and check your solution when solving an equation?
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