Two families visit a zoo. the entrance charge for adults and children aged 16 or over is £x. the entrance charge for children aged under 16 is £y. the first teo adults and three children aged 17, 12 and 10. they charged a toral of £51 to enter the zoo. the second family has two adults and four children aged 14, 11, 10 and 7. they are charged a total of £54 to enter the zoo. write down two simultaneous equations to show this information