aliasing folding phenomena in frequency domain matlab
Your plot is correct. You are sampling three waves $f_1 = 10\textrm{Hz}, f_2 = 30\textrm{Hz}$, and $f_3 = 70\textrm{Hz}$, with a sample frequency of $F_s = 1.5\times70\textrm{Hz} = 105\textrm{Hz}$. This means that your Nyquist frequency is $F_N = F_s/2 = 52.5\textrm{Hz}$, and corresponds to the maximum value of your frequency axis. 

As such, the signals $f_1$ and $f_2$ will be correctly sampled without problems, but the signal $f_3$ is higher than the Nyquist and so should appear as an alias (folded back into the sampled frequency range) at the frequency $f_{\textrm{alias}} = F_N-(f_3-F_N) = F_s-f_3 = 35\textrm{Hz}$. This is what you obtained.

If you want to create a plot similar to the one in the figure, then you could try to first sample your waves with a much higher sampling rate, in order to fully capture them all faithfully. Then, on the same plot, display what happens if you undersample with $F_N&lt;f_3$.