Suppose the two numbers are:

first number=x

second number=y

So

equation 1:

X-3=4y

equation 2:

X+Y=102

equation 2 can also be written as:

x=102-y

substituting this into equation 1:

102-y-3=4y

Subtracting:

99-y=4y

Shifting y to the other side:

99=4y+y

99=5y

Dividing:

y=99/5

So:

y=19.8

For x:

x=102-y

Substituting:

x=102-19.8

Subtracting:

x=82.2

So the two numbers are 19.8 and 82.2

first number=x

second number=y

So

equation 1:

X-3=4y

equation 2:

X+Y=102

equation 2 can also be written as:

x=102-y

substituting this into equation 1:

102-y-3=4y

Subtracting:

99-y=4y

Shifting y to the other side:

99=4y+y

99=5y

Dividing:

y=99/5

So:

y=19.8

For x:

x=102-y

Substituting:

x=102-19.8

Subtracting:

x=82.2

So the two numbers are 19.8 and 82.2