Solve the system:
x + y = 7
x − y = 1
Add the equations. The y-terms cancel:
2x = 8
x = 4
Substitute x = 4:
4 + y = 7
y = 3
Both equations are true at (4, 3), so that is the solution.

Solve the system:
x + y = 7
x − y = 1
Add the equations. The y-terms cancel:
2x = 8
x = 4
Substitute x = 4:
4 + y = 7
y = 3
Both equations are true at (4, 3), so that is the solution.
Where can two equations be true at once?
For y = x + 1 and y = −x + 5, set the expressions equal:
x + 1 = −x + 5
x = 2
y = 3
Both equations are true at (2, 3), so that intersection is the system’s solution.
Can you free x from the parentheses?
3(x + 2) = 18
3x + 6 = 18
3x = 12
x = 4
Distribute, subtract 6, then divide by 3. Check: 3(4 + 2) = 18.
A step-by-step Grade 8 lesson aligned with 8.EE.7b.
How can every value of x be correct?
x + 3 = x + 3
Subtract x from both sides and 3 = 3 remains. Because this statement is always true, every real number satisfies the original equation: infinitely many solutions.
Grade 8 standard 8.EE.7a.
When does an equation have no solution?
x + 2 = x + 5 simplifies to 2 = 5 after subtracting x from both sides. Because the result is a false statement, no value of x can satisfy the original equation.
A cinematic Grade 8 lesson aligned with 8.EE.7a.
Can you solve x + 3 = 7 before PuzzleVAI’s drone reaches the answer?
Subtract 3 from both sides. Equality is preserved, the variable is isolated, and x = 4.
A cinematic Grade 8 lesson on inverse operations and one-step linear equations aligned with 8.EE.C.7.
Lift a straight line without rotating it. What changes?
y = mx becomes y = mx + b.
The value b changes the line’s starting height, while m—and therefore the slope—remains unchanged. Same steepness, different y-intercept.
8.EE.6 | Math 8
Why does a straight line keep the same slope?
The right triangles formed along the line are similar. Their rise and run increase by the same scale factor, so the ratio rise ÷ run remains constant.
That constant ratio is slope.
8.EE.6 | Math 8
Which system has the greater unit rate?
Both rise for the same amount of time, but the gold system gains more. Therefore, its unit rate is greater.
For a proportional relationship, unit rate is also the slope of its graph and the value of m in y = mx.