$5000 is invested into two accounts. One pays 5% interest and the other pays 7%. The total investment earned $310 interest. Write the system of equations that describes this situation
and then solve the system to determine how much was invested at 5% interest and how
much was invested at 7% interest.

First, think of what you know. you know that the number t the end of the equation will need to be subtracted because it is the money he lost from buying the lawn mower. and your first two weeks have negative profit, so that tells you that c and d are wrong. now you can plug any of the weeks into a and b to see which one works. i'll start with plugging week 1 into a.this isn't right because it says your answer for week one should be -90.so now we need to try the same thing with b.this one got you the right answer, (sometimes if you only check with one of the weeks multiple will work so you need to check with more of the weeks, but it worked out fine here)this means that b is the correct answer.let me know if you need more clarification. i hope this : )

Where is the expression you want us to evaluate?