I have no ideal how to work this. I need help please.

Question

A sample of 30 of 178 funded projects revealed that 12 were valued at $17,360 each and 18 were valued at $20,280 each. From the sample data, estimate the total value of the funding for all the projects. (Enter your answers to two decimal places.)

Answer 1

12 + 18 = 30

12/30 = .4
.4* 178 = 71.2 at 17360
get it?

Answer 2

so I worked the other out like 12+18=3012/30+.6 then .6*178=106.8 then do I add these two together
106.8 +71.2=178.00