let

x = the first number

y = the second number

four times a first number decreased by a second number is 8

4x - y = 8

first number increased by twice the second number is 20

x + 2y = 30

by solving the system of equations

4x - y = 8

x + 2y = 30

we find that

x = 46/9

y = 112/9

the numbers are 46/9 and 112/9.