There are 42 students in sixth grade.
I don't see the answers, but it would most likely be 59 + x.
I'm assuming the funds earn 5% yearly?
Call x the amount he saves every year. The first year's deposit will be multiplied by 1.05 three times, the next will be multiplied by 1.05 twice, the third will be multiplied by 1.05 once, and the fourth will not generate interest (as it will immediately be used to buy the car).
Therefore, x(1.05^3+1.05^2+1.05+1)=21000, so 4.31x=21000. Dividing by 4.31, we see that x is approximately equal to 4872.
There is only one solution on the first one since you can't get 5 any other time then it being 7.
on the other one all real numbers above 7 are answers since after x is 7 it will be greater the. 5 always.
