t = 0:0.001:0.2;
w1 = 2.*pi.*35;
w2 = 2.*pi.*70;
A1 = 4;
A2 = 6;
x = A1.*sin(w1.*t) + A2.*sin(w2.*t);

X = abs(fft(x))./100;
w = 1000.*(0:200)./(200);

subplot(2,1,1);
plot(t,x);
subplot(2,1,2);
plot(w(1:25),X(1:25));