Can someone just explain how to find the answer?

You have 6 dollars +12 pennies +to quarters + 4 dimes=2 nickels how much do you have

Given that abcd is a rhombus, what is the value of x?

Parabolas y=−2x^2 and y=2x^2 +k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.