How many three-digit positive integers exist, all of whose digits are 2's and/or 5's?

  8

Step-by-step explanation:

There are two choices for each digit, and 3 digits, so 2^3 = 8 possible numbers. Here's a list:

  222, 225, 252, 255

  522, 525, 552, 555

d) by the cross product property, ab^2 = bc multiplied by ad

step-by-step explanation:

we are given

in the given triangle abc

angle a is 90° and segment ad is perpendicular to segment bc

we can see that

triangle(abc) and triangle(abd) are similar because they have common side and same angle (90 degree)

so, triangles(abc) and abd are similar

since, they are similar

so, the ratio of their sides must be equal

we get

now, we can cross multiply

and we get

so, this could be step to prove it

the first option is the answer.