1. The difference between two numbers is 7. If their sum is 25, find the two numbers by forming two equations and simultaneously by elimination method.

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2. Find the x and y of the following diagram. (photo is attached)

3. A man's age is three times his son's age. 10 years ago he was five times his son's age by forming two equations and solving them simultaneously find both of their present ages by substitution method.​

1. The difference between two numbers is 7. If their sum is 25, find the two numbers by forming two equations and simultaneously by elimination method.

1. The difference between two numbers is 7. If their sum is 25, find the two numbers by forming two equations and simultaneously by elimination method.

Jawaban:

y=3 dan x = 4

Penjelasan dengan langkah-langkah:

and this answer for number 2

to find the x and y of the following diagram

Gambar Jawaban

Jawab:

1. 16 and 9

2. x = 4 and y = 3

3. man = 60 years and son = 20 years

Penjelasan:

1.

a – b = 7

a + b = 25

—————– +

2a = 32

a = 32/2

a = 16

a – b = 7

a + b = 25

—————– –

-2b = -18

b = -18/-2

b = 9

So, a = 16 and b = 9

2.

x + 3y = 13

x + y = 7

—————— –

2y = 6

y = 6/2 = 3

substittute y = 3 into x + y = 7

x + y = 7

x + (3) = 7

x = 7 – 3 = 4

So, x = 4 and y = 3

3.

man = 3 x son

* 10 years ago:

(man – 10) = 5 x (son – 10)

substitute (man = 3 x son) into (man – 10) = 5 x (son – 10)

(man – 10) = 5 x (son – 10)

(3son – 10) = 5son – 50

3son – 5son = -50 + 10

-2 son = -40

son = -40/-2

son = 20 years

substitute son = 20 into man = 3 x son

man = 3 x son

man = 3 x (20)

man = 60 years

So, the present age of the man is 60 years and the son is 20 years