Answer 7 and 8 and give the example

7. For this one, we need an equation. Lets make x = the price of the computer. Since the price of the printer is 30% the price of the computer, we can make that .3x, because a number multiplied by .3 will give you 30% of your original number. So, our equation will be:

Since x is the cost of the computer, you have your answer right there. The computer costs $2,028.

8. For this one we're going to need a proportion, but first we need to find out how much of the percentage of seeds Cliff planted. 
% of seeds planted per person:
Ali - 40
Ben - 45
Cliff - x
All percentages add up to 100, so we'll make an equation to figure this out:

Therefore, Cliff planted 15% of the seeds. Since Cliff planted 15% of the seeds, and he planted 87 total, 15% of our total number of seeds planted is 87. We can now make a proportion to figure out how many seedlings were planted all together.

We can now cross multiply in order to get a solvable equation:

The total number of seedlings planted was 580. 

Sorry if this is confusing at all, hope I helped!