Answer:

7

Step-by-step explanation:

2 : 90 = ? : 315

2 × 315 = 630

630 ÷ 90 = 7

So the answer is 7.

Answer:

7 teacher

Step-by-step explanation:

90 ÷ 2 = 45

315 ÷ 45 =7

There are 1 teacher per 45 pupils,

so therefore there are 7 teacher for 315 pupils