What are 3 detailed reasons to join the allied powers?

Churchill and US President Franklin Delano Roosevelt had been working together for some time when the United States entered the war in 1941. Roosevelt believed a British victory over the Axis was in America’s best interests, while Churchill believed such a victory was not possible without American assistance. In 1940, the two leaders worked to find ways for America to help Britain hold on without violating its neutrality. The following year they met off the coast of Newfoundland to begin planning, in sweeping terms, the postwar world. Soviet Premier Joseph Stalin was a late addition to the Big Three. On New Year’s Day 1942, representatives of all three nations signed the United Nations Declaration, pledging to join hands to defeat the Axis powers.

there is no photo, therefore i can not answer your question.

where's the