Question

There are some lotus flowers in a lake. If one butterfly sits on each flower, one butterfly is left. If two butterflies sit on each flower, one flower is left. What is the number of flowers and butterflies.

Answer 1

the number of butterflies = x



the number of flowers = y



Given that if there is one butterfly for one flower, there is one flower
left.



=> y = x + 1



Also, if there are two butterflies on each flower, there is one flower
left.



=> y = 2(x - 1)



Thus,



x + 1 = 2x - 2



x - 2x = -2 -1



-x = -3



=> x = 3



The number of butterflies = x = 3.


The number of flowers = y = x + 1 = 3 + 1 = 4.