maths question help?

Henrik___Rob
x________y
3_______ 2

x+ 20___y + 20
4________2

x/y = 3/2
2x = 3y

[x + 20] / [y + 20] = 2
x + 20 = 2y + 40
2x - 2y = 20
x - y = 10

3y - y = 10
2y = 10
y = 5

x = 15

Henrik earns £15 in the week before Christmas

There's a problem with your question. If they both get an equal bonus of £20, it should have a greater effect on Rob's earnings. But the ratio goes from 3:2 up to 4:2 which means Henrik now has an even larger share.

I'll show you how to solve this, but we are going to get negative numbers:

Let 3x be the amount that Henrik normally earns
Let 2x be the amount that Rob normally earns

If we add £20 to each, the ratio is now 4:2 (or 2:1)
(3x + 20) / (2x + 20) = 2/1
3x + 20 = 2(2x + 20)
3x + 20 = 4x + 40
-20 = x
x = -20

Henrik earns -60
Rob earns -40
The ratio is -60/-40 = 3:2

After getting their bonuses, Henrik now earns -40 and Rob earns -20 and the ratio is 4:2.

Answer:
Henrik earned -40 with the bonus.

Please repost the question with the correct details.