Funfair Adults C62170
1. **State the problem:**
We need to find the number of adults at a funfair given relationships between adults, boys, and girls.
2. **Define variables:**
Let $B$ = number of boys, $G$ = number of girls, and $A$ = number of adults.
3. **Given information:**
- There were 120 more adults than boys: $$A = B + 120$$
- There were \(\frac{3}{4}\) as many boys as girls: $$B = \frac{3}{4}G$$
- The number of boys was 12% of the total number of people: $$B = 0.12 (A + B + G)$$
4. **Express total people in terms of $B$ and $G$:**
Total people = $$A + B + G$$
Using $A = B + 120$, total = $$B + 120 + B + G = 2B + G + 120$$
5. **Substitute $B = \frac{3}{4}G$ into total:**
$$2B + G + 120 = 2\left(\frac{3}{4}G\right) + G + 120 = \frac{3}{2}G + G + 120 = \frac{5}{2}G + 120$$
6. **Use the percentage equation:**
$$B = 0.12 (A + B + G)$$
Substitute $B = \frac{3}{4}G$ and $A = B + 120$:
$$\frac{3}{4}G = 0.12 \left( (\frac{3}{4}G + 120) + \frac{3}{4}G + G \right)$$
Simplify inside parentheses:
$$\frac{3}{4}G = 0.12 \left( \frac{3}{4}G + 120 + \frac{3}{4}G + G \right) = 0.12 \left( \frac{3}{4}G + \frac{3}{4}G + G + 120 \right)$$
$$= 0.12 \left( \frac{3}{4}G + \frac{3}{4}G + G + 120 \right) = 0.12 \left( \frac{3}{4}G + \frac{3}{4}G + G + 120 \right)$$
Sum the $G$ terms:
$$\frac{3}{4}G + \frac{3}{4}G + G = \frac{3}{4}G + \frac{3}{4}G + \frac{4}{4}G = \frac{10}{4}G = \frac{5}{2}G$$
So:
$$\frac{3}{4}G = 0.12 \left( \frac{5}{2}G + 120 \right)$$
7. **Solve for $G$:**
$$\frac{3}{4}G = 0.12 \times \frac{5}{2}G + 0.12 \times 120$$
$$\frac{3}{4}G = 0.3G + 14.4$$
Bring terms with $G$ to one side:
$$\frac{3}{4}G - 0.3G = 14.4$$
Convert to decimals:
$$0.75G - 0.3G = 14.4$$
$$0.45G = 14.4$$
$$G = \frac{14.4}{0.45} = 32$$
8. **Find $B$ and $A$:**
$$B = \frac{3}{4} \times 32 = 24$$
$$A = B + 120 = 24 + 120 = 144$$
**Final answer:**
There were **144** adults at the funfair.