answer of the first exercise

1) For this typical french meal :

 Yvette ate 6 snails and 8 frogs.

Jean-Claude ate 4 snails and 12 frogs.

Ginette ate 3 snails and 2 frogs.

Gérard ate 5 snails and 3 frogs.

And Gertrude ate 4 snails and 3 frogs.

At the end of  the evening 22 snails and 28 frogs were eaten.

2) We know that 2 snails cost 3 euros and 1 frog costs 2 euros so :

2 x 28 = 56 euros

2 snails = 3 euros

22 sanils =? –> (22 x 3) / 2 = 33 euros

The result is 33 + 56 = 89 euros

The family must pay 89 euros for Christmas