1. the ages is of juan and his sister add up to half their father's age> if juan is 3 yrr than older than his sister and 27 yr younger than his father how many yrs old is juan
2.altogether, 6 chicks eat 8 cups of grains in 3 days. how many cups ofgrain will 3 chicks eat in 9 days
3.an odd whole number between 600 and 800 is divisible by 7 and9> what is the sum of its digits.
4.what is the value of 1-2+3-4+5-6+...+53- 54+55