Resuelve el siguiente sistemas de ecuaciones por el método de sustitución
83x - 20y = 590
60x + 18y = 816

x=10 and y=12

Step-by-step explanation:

To solve this quadratic equation we will use two method

1. Elimination method

2. substitution method

first of we use elimination method

we either eliminate x or y

we will be eliminating y

83x-20y=590(eq1)

60x+18y=816(eq2)

y will be eliminated by multiplying

(eq1) by 9

(eq2) by 10

which will give

747x-180y=5310(eq3)

600x-180y=8160(eq4)

see that y has the same value that is (-180y and +180y)

so to eliminate y completely you have to add eq1 and eq2 because if you don't add them together you wont eliminate y

747x-180y=5310

+

600x+180y=8160

=

1347x+0=13470

1347x=13470

x=13470/1347

x=10

Now to find y we use substitution method ie put x=10 in any of the equation above(eq1,eq2,eq3, eq4) you will get the same answer

eq1

83x-20y=590 where (x=10)

83(10)-20y =590

830-20y=590

like terms

-20y=590-830

-20y= -240

divide both sides with -20

y= -240/-20

y=12

OR

eq2

60x+18y=816 where x=10

60(10)+18y=816

600+18y=816

like term

18y=816-600

18y=216

y=216/18

y= 12

or eq3 or eq4 you will still get the same answer

a.   since the profit made in 2012 is equal to the profit made in 2014, the profit is symmetric about the line y = 120,000.

step-by-step explanation:

step-by-step explanation: