Question

An interior decorator must mix red and white paint in the ratio of 2:5 in order to obtain the correct colour pink. If she needs 28 litres of pink paint, calculate how much red paint and how much white paint shem must use to obtain the right colour.

Answer 1

Let x = red paint

2/7 = x/28

Answer 2

r = litres of red paint
w = litres of white paint

r + w = 28

r/w = 2/5

so: 5r = 2w which leads to
r = (2/5)(w)
Replace r in the first equation with the (2/5)(w)
that will give you 7/5 w = 28

Can you finish from here?