The ratio of boys to girls in a class is 4:5. If there are 80 boys, how many girls are there?

$$8x - 7$$

Jibu sahihi ni A.

2. Tatua kwa x: $5x - 3 = 17$

$$5x - 3 + 3 = 17 + 3$$ $$5x = 20$$

$$\frac{5x}{5} = \frac{20}{5}$$ $$x = 4$$

Jibu sahihi ni B.

3. LCM ya 15 na 25 ni ipi?

$$15 = 3 \times 5$$ $$25 = 5 \times 5 = 5^2$$

$$\text{LCM}(15, 25) = 3^1 \times 5^2$$ $$\text{LCM}(15, 25) = 3 \times 25$$ $$\text{LCM}(15, 25) = 75$$

Jibu sahihi ni C.

4. Rahisisha: $2(x + 3) + 4(x - 1)$

$$2(x + 3) = 2x + 6$$ $$4(x - 1) = 4x - 4$$

$$(2x + 4x) + (6 - 4)$$ $$6x + 2$$

Jibu sahihi ni C.

5. Uwiano wa wavulana kwa wasichana darasani ni 4:5. Ikiwa kuna wavulana 80, kuna wasichana wangapi?

Acha $G$ iwe idadi ya wasichana.

$$\frac{80}{G} = \frac{4}{5}$$

$$4 \times G = 80 \times 5$$ $$4G = 400$$

$$G = \frac{400}{4}$$ $$G = 100$$

Jibu sahihi ni A.

Majibu ya mwisho:

1. A) $\boxed{\text{8x - 7}}$
2. B) $\boxed{\text{x = 4}}$
3. C) $\boxed{\text{75}}$
4. C) $\boxed{\text{6x + 2}}$
5. A) $\boxed{\text{100}}$