You use 4 boxes of rice to serve 13 people. if you want to serve 39 people, what should you do?

Use times as many boxes of rice

Step-by-step explanation:

we know that

Using proportion

original quantity of boxes ----->  

boxes needed ----->  

therefore

Use times as many boxes of rice

a_n = a_1 + (n - 1)d

the first term is 6.

the common difference d = ?

when you find d, replace n with 7 and d with the common difference to find your answer.