Question

Could you give me a crash course on how to solve these?

Answer 1

first one is just playing with similiar triangles; the second ones has me a little perplexed

Answer 2

...

Answer 3

ratios and proportions on the first setup ... i still got no idea about the second

Answer 4

spose you have similar shapes; we can create a ratio of the measures of one shape: a/b
and compare it to the ratio of the similar shape: A/B

a proportion is when a/b = A/B

Answer 5

in your first setup you have pretty much:

therefore the ratio: a/b would have to equal the ratio: (a+c)/(b+d)

the rest is just algebra