How many four-digit whole numbers are there such that the leftmost digit is odd, the second digit is even, and all four digits are different?

There are 1400 different combinations.

Step-by-step explanation:

The conditions are:

we have 4-digits: abcd.

all the digits are different.

a is an odd number, and b is an even number.

Then, for a, we have the options 1, 3, 5, 7 and 9 (so we have 5 options).

for b, we have the options 0, 2, 4, 6 and 8 (so we have 5 options).

for c, we can have odd or even numbers, so we have 8 options ( remember that there where 2 numbers already taken away, this is why we have only 8 options).

for d we have 7 options (because 3 numbers are already taken).

Then the number of combinations is equal to the product of the number of options for each selection:

C = 5*5*8*7 = 1400

show us the picture

step-by-step explanation:

show the !

∠1≅∠2 by the alternate exterior angles theorem.

step-by-step explanation:

given, a ∥ b and ∠1 ≅ ∠3 .we have to prove that e ∥ f

we know that ∠1≅∠3 and that a || b because they are given. we see that by the alternate exterior angles theorem. therefore, ∠2≅∠3 by the transitive property. so, we can conclude that e || f by the converse alternate exterior angles theorem.

we have to fill the missing statement.

transitivity property states that if a = b and b = c, then a = c.

now, given ∠1≅∠3 and by transitivity property ∠2≅∠3 .

hence, to apply transitivity property one angle must be common which is not in result after applying this property which is ∠1.

the only options in which ∠1 is present are ∠1 and ∠2, ∠1 and ∠4

∠1 and ∠4 is not possible ∵ after applying transitivity we didn't get ∠4.

hence, the missing statement is ∠1≅∠2.

so, ∠1≅∠2 by the alternate exterior angles theorem.