Question

What is x and y of 2x-4y=10&x+5y=40​

Answer 1

`x = 15, y = 5`

Explanation:

We are given that

`2x - 4y = 10\\x + 5y = 40`

When given these types of equations, we can manipulate them in order to cancel out a variable. Cancelling either the x or y works, choose which one is easier.

In this case, we can multiply the second equation by -2 and easily cancel out the x's

`2x - 4y = 10\\-2x - 10y = -80`

Now we can add the two equations

`-4y + (-10y) = 10 + (-80)\\-4y - 10y = -70\\-14y = -70\\y = 5`

We can substitute y into the second equation and solve for x

`x + 5(5) = 40\\x + 25 = 40\\ x = 15`

Check:

2(15) - 4(5)

30 - 20 = 10

it works