7th Grade Math

Solve Addition Equations

Solve x + 6 = 4. Check your solution.

x + 6 = 4 Write the equation.

• 6 = - 6 Subtraction Property of Equality
  x = - 2 Simplify.
  Check x + 6 = 4 Write the original equation.


• 2 + 6  4 Replace x with -2.
  4 = 4 ✓ The sentence is true.
  The solution is -2.

Solve each equation. Check your solution.

a. y + 6 = 9 b. x + 3 = 1 c. - 3 = a + 4

MARINE BIOLOGY Clown fish and angelfish are popular tropical

fish. An angelfish can grow to be 12 inches long. If an angelfish

is 8.5 inches longer than a clown fish, how long is a clown fish?

Words

Variable

Modelz

Equation

An angelfish is longer than^ 8.5 inches a clown fish.

Let c represent the length of the clown fish.

angelfish, 12 inches

clown fish

c 8.5 inches

12 = c + 8.5

12 = c + 8.5 Write the equation.

• 8.5 = - 8.5 Subtraction Property of Equality
  3.5 = c Simplify.
  A clown fish is 3.5 inches long.

d. WEATHER The highest recorded temperature in Warsaw,

Missouri, is 118°F. This is 158° greater than the lowest recorded

temperature. Write and solve an equation to find the lowest

recorded temperature.

Lesson 1D Addition and Subtraction Equations 209

Solutions Solutions Notice that

your new equation, x = –2,

has the same solution as

the original equation,

x + 6 = 4.

Real-World Link

The deeper the descent

of a dive, the quicker

the diver consumes air.

Most divers can spend

45 minutes to an hour

at 40 feet below the

surface.

RR

T

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