t=0:0.01:4;
p1=20+10*cos(2*pi*t);
p2=exp(t); (or whatever Matlab use for exponential function)
plot(t, p1, '--', t, p2, '.');
xlabel('time');
ylabel('money');
I think I got all of it, I do not have Matlab at home so I can not check it. You might want to play with it a little to make sure it works exactly right.