the sum of two numbers is 4 less than twice the larger. if the large is decreased by three times the smaller, the result is - 20.

Let x be the larger number and y be the smaller number.

Eq'n 1: x + y = 4 - 2x

Simplify ...

x + 2x = 4 - y

3x = 4 - y

y = 3x - 4

Eq'n 2: x - 3y = - 20

Plugging in the y from the Eq'n 1.

x - 3 (3x - 4) = - 20

x - 9x + 12 = - 20

-8x = - 20 - 12

-8x = - 32

x = 4

now we have the x, for us to get the y, we have to substitute the x from any of the 2 Eq'ns above.

x + y = 4 - 2x

so if x = 4

4 + y = 4 - 2 (4)

4 - 4 + y = - 8

y = - 8

so we can say the larger number "x" is 4 and the smaller one which is "y" is - 8