1.Alan is x years old .Tom is 5 years older than Alan. Write an expression for the total of their ages.
2.There are 100 students. 49 of the 100 students are girls. 10 of the girls came by car. 16 boys walked. 21 of the 41 students who came by bicycle are boys. Work out the total number of students who walked to school.
3.The ratio of dogs to cats is 1:3 and cats to rabbits is 1:6. What is the ratio of dogs to rabbits?
4.Round 435 to one significant figure