Answer:
Step-by-step explanation:
First we are going to set up our general equation (what is being asked of us). Marina bought pears, pineapples, and kiwis and spent $13.50 on them. The equation for that is
pi + pe + k = 13.5
Now we need to figure out how to eliminate most of those unknowns and put 2 of them in terms of the other 1. It looks like everything is based on the number of pineapples she bought. First it says she bought 9 more pears than pineapples, so obviously, there are more pears than pineapple, so
pe = pi + 9
And if she bought 2 fewer than kiwis thatn pears, and pears = pi + 9, then the number of kiwis she bought was
kiwis = (pi + 9) - 2 which simplifies down to pi + 7.
Now we'll put all of those into the equation:
pi + (pi + 9) + (pi + 7) = 13.5 What I have done is create an equation that is not parallel. In other words, I have the NUMBER of the kinds of fruit on one side of the equation, and the COST of the fruit on the other side, and that's not cool. We have to have EITHER a NUMBER of fruit equation OR a COST of fruit equation, but not both in the same equation. To amend that, we will figure in the cost of each of these kinds of fruit by the correcpsonding number of that kind of fruit. Pineapples cost $1.50 each, so the expression for pineapples is 1.5pi; pears cost $.50 each, so the expression for pears is.5(pi + 9); kiwis cost $.30 each, so the expression for kiwis is .3(pi + 7). NOW we can set up the equation:
1.5pi + .5(pi + 9) + .3(pi + 7) = 13.5 and simplify:
1.5pi + .5pi + 4.5 + .3pi + 2.1 = 13.5 and simplify some more by combining like terms:
2.3pi = 6.9 so
pi = 3. Ok we have 3 pineapples. Now we go back up to the expression for pears:
pe = pi + 9 so
pears = 12. Now we go back to the expression for kiwis:
k = pi + 7 so
kiwis = 10. And there you go!
