Divide both sides by 6:

$\frac{6x}{6} = \frac{42}{6}$

$x = 7$

Check: $6(7) = 42$ ✓

Answer: $x = 7$

Multiply both sides by $-5$:

$-5 \times \frac{x}{-5} = 9 \times (-5)$

Step 1: Identify the operation. x is being divided by 5

Step 2: Use inverse operation (multiply by 5). Multiply both sides by 5: 5 × (x/5) = 5 × 8

Step 3: Simplify. x = 40

Step 4: Check. 40/5 = 8 ✓

Answer: x = 40

Step 1: Define the variable. Let x = money you started with

Step 2: Write the equation. Starting money - spent = left x - 15 = 42

Step 3: Solve (add 15 to both sides). x - 15 + 15 = 42 + 15 x = 57

Step 4: Check. $57 -$15 = $42 ✓

Step 5: Answer the question. You started with $57

Answer: x = 57; You started with $57