Lisa was keeping a record of the sales she had made for the contest. The first and second weeks she sold 18 boxes of cookies each week. The third and fourth weeks she sold 12
each week, and the fifth week she sold 15 boxes. How many boxes of cookies did Lisa
sell altogether?
=N
=N​

Lisa sold 75 boxes of cookies all together

Explanation:

The 1st week she sold 18 boxes of cookies

The 2nd week she sold 18 of cookies

The 3rd week she sold 12 boxes of cookies

The 4th week she sold 12 boxes of cookies

The 5th week she sold 15 boxes of cookies

So, number of cookies sold altogether is 18+18+12+12+15= 75

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.