We describe a universal procedure that allows to obtain continuous solutions of inequalities of the form \(\begin{aligned} a_1f(\alpha _1x+(1-\alpha _1)y)+\cdots +a_nf(\alpha _nx+(1-\alpha _n)y)\le 0,\;x,y\in I, \end{aligned}\) where \(I\subset {\mathbb {R}}\) is an interval, \(f:I\rightarrow {\mathbb {R}}\) is an unknown function and \(a_i\in {\mathbb {R}},\) \(\alpha _i\in [0,1]\) are given numbers. After presenting and explaining all necessary theoretical details, we provide a computer program that solves inequalities of such type.