I’m single and ready to mingle only 13-17 year olds. I am 40 and very sus

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Given a: b and b: c, find a: b: c. write the ratio in simplest form. a: b=6: 10 and b: c=21: 33

An investment decreases in value by 30% in the first year and decreases by 40% in the second year. what is the percent decrease in percentage in the investment after two years