In rectangle klmn, km =6x +16 and ln =49. find the value of x

The answer is 5.5

In a rectangle, lengths of diagonals are equal. If you draw the rectangle, you can see that KM and LN are diagonals, so they must be equal:
KM = LN

KM = 6x + 16
LN = 49

6x + 16 = 49
6x = 49 - 16
6x = 33
x = 33/6
x = 5.5

The answer is c because you turn 17.5% into a decimal which gives you .175 then you times that by $361.35 which gives you 63.23625 but then you round that which gives you 63.24. then you at 63.24 pulse 361.35 and you round it which gives you $425