Which of the problems below is not a permutation? the number of ways 20 people can finish in the first three places in a race. how many different kinds of pizzas can be made with 12 optional toppings. how many ways 15 people can arrange themselves in a straight line. how many ways the top 20 hit songs can be arranged from a selection of 500 current singles.

Permutation is defined as the possible combinations or variation in which a number of things can be ordered or arranged.    

All the examples provided are permutation, except -- How many different kinds of pizzas can be made with 12 optional toppings.  

Other examples are clear examples of permutations. With permutations, order matters.

∠lno ≅ ∠lnm

∠oln ≅ ∠mln

step-by-step explanation:

given   that triangle lno is congruent to triangle lnm.

we have to fill up the blanks in the given question.

according to above order of congruency   kept in mind we can say that

∠lno ≅ ∠lnm

∠oln ≅ ∠mln

ln ≅ ln due to common in both.

hence, by sas congruency,

the side angle side rule   states that if two sides and the included angle of one triangle are congruent to another triangle, then these two triangles are congruent.