Resolver las siguientes ecuaciones lineales de 2x2, aplicando el método de sustitución:

a) x = 28

   y = 4

b)

Step-by-step explanation:

a) x- 5y = 8

-7 + 8y = 25

8x-40y = 64

-35 + 40y = 125

8x-35 = 189

8x = 189 + 35

8x = 224

x = 28

x-5y = 8

28-5y = 8

28-8 = 5y

20 = 5y

y = 4

b) Sistema de ecuaciones lineaes " 2 × 2 " : Metodo de sustitucion

1 → { 4x + 5y = 5

2 → { - 4x - 10y = - 7

Despejando la variable " y " de la ecuacion " 1 " :

4x + 5y = 5

5y = - 4x + 5

y = ( - 4x + 5 ) / 5

Reemplazamos en la ecuacion " 2 " :

- 4x - 10 ( - 4x + 5 ) / 5 = - 7

- 4x - 2 ( - 4x + 5 ) = - 7

- 4x + 8x - 10 = - 7

- 4x + 8x = - 7 + 10

4x = 3

x = 3/4

Reemplazamos en la ecuacion " 1 " de la variable despejada " y " :

y = ( - 4.(3/4) + 5 ) / 5

y = ( - 3 + 5 ) / 5

y = 2/5

Solución → S = {( 3/4 , 2/5 )}

stop using this to cheat on home work

step-by-step explanation:

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answer: 1,380

step-by-step explanation:

1: you turn %15 into a decimal by moving the decimal point two places to the left.

2: and then you multiply .15 by 1,200 , which will get you 180.00

3: from there you will add 180 to 1,200

4: which will get you 1,380

hope it *im kind of slow so idk if my answer is right*