Given,
350 square feet requires 1 gallon of paint
To assign gallons of paint with the amount of paint required for wall area.
Since 350 square feet requires 1 gallon of paint
350/350 square feet will require 1/350 gallon of paint
1 square feet requires 1/350 gallon of paint
That is, for each square meter area of wall, 1/350 gallon of paint is required
Each square meter area of wall requires 1/350 gallon of paint
Therefore, x square meter area of wall requires x/350 gallon of paint
Mathematically,
If x is the area of wall in square meters,
And y is the amount of paint required in gallons
y = x/350
For instance, for 250 square meter area of wall
x = 350
y = x/350
y = 250/350
y = 0.714285714286
Amount of paint required = 0.714285714286 gallons