In a demographic study of four different villages, the data shows that the total sum of populations across all four villages is 6,400. The combined total number of males across these villages is 2,900 and the combined total number of females is 2,640. Given that the total population of a village equals the number of Males + Females + Children, find the total number of children in the four villages.

In a data table, the production of rice for country Q and country R is 60 lakh tons and 54 lakh tons respectively. The production of wheat for country S and country T is 52 lakh tons and 52 lakh tons respectively. What is the ratio of the total production of rice of countries Q and R to the total production of wheat of countries S and T?

In a survey of 5 countries (P, Q, R, S, T), the rice production values are 40, 60, 54, 70, and 51 lakh tons respectively. What is the average production of rice (in lakh tons) across all 5 countries?