charles77479a wrote:

1:if x and 10 are relatively prime natural numbers, then x could be a multiple of

a: 9

b: 18

c:4

d:25

e:14

Relative prime numbers are numbers which have 1 as their Greatest common factor.

look at the Q, it says could be. lets look for which cannot be

18, 10 have 2 as a common divisor which is > 1

(4,10) (25,10) (14,10) all have divisors such as 2, 5 which are greater than 1. If the numbers themselves have GCF's other than 1, their multiples also will have GCF other than 1.

(9,10) have their greatest common factor as 1. even though (18,10) have 2 as common factor, 9 still serves our answer "could be"

2:the area of ADE is 12 square units. If B is the midpoint of AD and C is the midpoint of AE, what is the area of ABC.

a:2 s/u

b:3 s/u

c:3.5 s/u

d:4 square units

e: 6 square units

Once we figure out that these triangles are similar triangles, we need to

Area of large triangle = (s ^ 2) * area of small triangle

where s is similarity ratio. We see that each side of big triangle is twice the small triangle

12 = 4 * area of small triangle -> 3

I know the answer to these questions; however, i do not understand how to solve the problem. If someone could explain them in details, i would really appreciate it. Thank you very much.