How do you solve the system of equations 8x-9y=158x−9y=15 and -x+4y=1−x+4y=1 by combining the equations.

x = 3 and y = 1

Step-by-step explanation:

Give system of equations are :

8x-9y=15 ...(1)

−x+4y=1 ...(2)

Multiply equation (2) by 8.

−8x+32y=8 ..(3)

Add equation (1) and (3).

8x-9y -8x + 32y = 15+8

23y = 23

y = 1

Put the value of y in equation (2).

−x+4(1)=1

-x = -4+1

x = 3

Hence, the values of x and y are 3 and 1.

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step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional