Unsure of how to start the algebraic proccess of combining these two equations:

v_{2}=v_{1}+aΔt and Δd=v_{1}Δt+1/2aΔt^{2} ,

The attached is a screenshot of the course material that I need help with. It demonstrates how to combine the two equations but it seems to skip some steps that I can’t quite catch. I gathered to do so I should substitute one equation into the other, but do not know where to start. Some guidance would be greatly appreciated. Thank you

http://ift.tt/1hepvG3