According to a proper production function, if adding one unit of capital increases output by 10 units, adding an another unit of capital beyond that must increase capital by

less than 10 units

Explanation:

The production function represent the diminishing marginal returns

Here diminishing marginal returns means that marginal output i.e. generated an extra unit would continue to reduce more units of input that are used

So if we add one unit of capital that increased the output by 10 units so if another unit if capital is added so it increased the output but that should be less than 10 units

if you use only 25 for your entertainment and only 200 for the groceries that you really need and take out the 50 per month for the computer then that should be enough