Flower Arrangement E94855
1. **State the problem:** A bride and groom are arranging flowers. The bride finishes one arrangement in $x$ minutes, and the groom finishes one arrangement 8 minutes later, i.e., in $x+8$ minutes. Together, they complete 40 arrangements in 3 hours (180 minutes). We need to find how fast the bride is (value of $x$) and how many arrangements she made by herself.
2. **Write the formula:** The rate of work for the bride is $\frac{1}{x}$ arrangements per minute, and for the groom is $\frac{1}{x+8}$. Together, their combined rate is $\frac{40}{180} = \frac{2}{9}$ arrangements per minute.
3. **Set up the equation:**
$$\frac{1}{x} + \frac{1}{x+8} = \frac{2}{9}$$
4. **Solve the equation:**
Multiply both sides by $x(x+8)$ to clear denominators:
$$ (x+8) + x = \frac{2}{9} x (x+8) $$
Simplify left side:
$$ 2x + 8 = \frac{2}{9} (x^2 + 8x) $$
Multiply both sides by 9:
$$ 9(2x + 8) = 2(x^2 + 8x) $$
$$ 18x + 72 = 2x^2 + 16x $$
Bring all terms to one side:
$$ 0 = 2x^2 + 16x - 18x - 72 $$
$$ 0 = 2x^2 - 2x - 72 $$
Divide entire equation by 2:
$$ x^2 - x - 36 = 0 $$
5. **Factor the quadratic:**
$$ (x - 6)(x + 6) = 0 $$
So, $x = 6$ or $x = -6$. Since time cannot be negative, $x = 6$ minutes.
6. **Interpret the result:** The bride takes 6 minutes per arrangement.
7. **Calculate how many arrangements the bride made alone:**
The bride's rate is $\frac{1}{6}$ arrangements per minute.
In 180 minutes, she would make:
$$ 180 \times \frac{1}{6} = 30 $$ arrangements.
**Final answers:**
- Bride's time per arrangement: $6$ minutes
- Number of arrangements bride made alone: $30$