From the graph, the national debt in 1960 was 46%.
It was given that the national debt in 1960 is $0.3 trillion.
Let the GDP be represented by G. This means that 46% of this value is:
![\Rightarrow(46)/(100)* G](https://img.qammunity.org/2023/formulas/mathematics/high-school/d4hhb5q5bcf44jr19o3ghittb6qfxm1txe.png)
Equating this to the debt amount, we have:
![0.3=(46)/(100)* G](https://img.qammunity.org/2023/formulas/mathematics/high-school/cjdp2fa1uh93mfzajdke2z9p7cg0d59xt5.png)
Solving for G, we have:
![\begin{gathered} 46G=0.3*100 \\ 46G=30 \\ G=(30)/(46) \\ G=0.65 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/y2kzsann9ma8iyfpoeogxjvp43rvcgwiev.png)
Therefore, the GDP in 1960 was $0.65 trillion.